Here is an array of pseudo-primes for those who like to test it:

$pseudoprimes = array(9,15,21,25,27,33,35,39,45,49,51,55,57,63,65,69,75,77,81,85,87,91,93,95,99,105,121,133,185,217,273,301,305,323,325,341,377,481,511,561,585,645,657,671,703,705,781,793,817,949,989,1001,1105,1111,1159,1233,1261,1281,1333,1387,1417,1541,1661,1729,1825,1829,1891,1905,2047,2101,2257,2353,2465,2501,2665,2701,2737,2821,2981,3201,3239,3277,3281,3367,3421,3565,3589,3641,3745,3751,3827,3913,4033,4097,4181,4187,4369,4371,4525,4577,4641,4681,4921,4961,5041,5185,5459,5461,5551,5611,5713,5777,6305,6533,6541,6601,6697,6721,7161,7381,7449,7777,7813,7957,8113,8149,8321,8365,8401,8481,8911,9071,9179,9265,9709,10001,10225,10261,10585,10745,10877,11041,11111,11137,11419,11521,11663,12025,12209,12403,12545,12801,13021,13201,13333,13665,13919,13981,14089,14701,14839,14981,15251,15457,15709,15751,15841,16109,16211,16297,16531,16705,17119,17329,17711,18361,18407,18705,18721,18971,19043,19345,20017,20197,20417,20425,21049,21361,22049,22499,23407,23521,23653,24211,24465,24569,24661,25199,25351,25761,25829,25877,26069,27323,27971,28009,29281,29341,29539,29681,29857,29891,30121,30673,30739,30857,30889,31021,31621,31631,31697,32759,33153,34441,34561,34943,34945,35207,35425,35785,36301,38081,39059,39203,39305,39331,39493,39689,40309,40501,41041,42799,43621,44099,44173,44287,44801,46657,46979,47197,47641,47879,48133,49141,49241,49321,50183,50881,51841,51983,52633,52701,53663,53971,54705,55969,56033,58519,58825,60377,63139,63973,64079,64681,67861,67921,68251,72041,72389,73919,74593,75077,75241,75361,76627,78937,79381,80189,90061,90241,96049,97439,97921,98173,100065,100127,100651,102311,105281,113573,115639,118441,125249,130139,137549,137801,146611,153931,155819,158399,161027,162133,162401,163081,172081,176399,176471,186961,189419,192509,197209,197801,218321,219781,224369,230691,231703,243629,249331,252601,253259,254321,257761,268349,268801,271441,272611,288919,302101,313499,324899,370229,399001,429479,430127,449065,459191,473891,480689,488881,530881,600059,621781,632249,635627,656601,670033,741751,838201,851927,904631,997633,1024651,1033997,1050985,1106327,1149851,1256293,1317121,1388903,1392169,1533601,1615681,1653601,1690501,1697183,1773289,1857241,2113921,2263127,2433601,2435423,2455921,2662277,2704801,3057601,3175883,3218801,3224065,3338221,3399527,3452147,3581761,3664585,3774377,3828001,3900797,3967201,4109363,4226777,4403027,4463641,4828277,4870847,4903921,5481451,7405201,7640137,7678321,8539786,9264097,9439201,9532033,9582145,10237921,12813274,16532714,17340938,24658561,27422714,27664033,31150351,33940178,46672291,64132426,89733106,95173786,102690901,109437751,130944133,139952671,178482151,187473826,196075949,203211098,214038533,234735586,284301751,353686906,383425351,395044651,407282851,417027451,498706651,517697641,545670533,582799951,612816751,799171066,801123451,855073301,903136901,919831058,970355431,1091327579,1133818561,1188287794,1235188597,1389675541,1502682721,1955272906,2059739221,2166139898,2304156469,2309861746,2864860298,2976407809,3273820903,3841324339,3871638242,3924969689,4982970241,5130186571,5242624003,5313594466,5867301826,6335800411,7045248121,7279379941,7825642579);


On request I can send more details about it.

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