This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A341662 #12 Mar 04 2021 01:43:28 %S A341662 53,67,131,139,227,277,283,347,383,641,653,661,821,877,997,1069,1181, %T A341662 1213,1811,2083,2389,2459,2819,3803,4021,4253,4723,6619,6829,7213, %U A341662 7933,8069,9013,9187,10589,11261,16139,17827,18133,18587,19309,19541,20477,20947 %N A341662 Primes p such that p^4 - 1 has 160 divisors. %C A341662 Conjecture: sequence is infinite. %C A341662 For every term p, p^4 - 1 is of the form 2^4 * 3 * 5 * q * r * s, where q, r, and s are distinct primes > 5, with three exceptions: p = 53, 383, and 641 (see Example section). %e A341662 p = %e A341662 n a(n) p^4 - 1 factorization of p^4 - 1 %e A341662 -- ---- ------------ ------------------------------- %e A341662 1 53 7890480 2^4 * 3^3 * 5 * 13 * 281 %e A341662 2 67 20151120 2^4 * 3 * 5 * 11 * 17 * 449 %e A341662 3 131 294499920 2^4 * 3 * 5 * 11 * 13 * 8581 %e A341662 4 139 373301040 2^4 * 3 * 5 * 7 * 23 * 9661 %e A341662 5 227 2655237840 2^4 * 3 * 5 * 19 * 113 * 5153 %e A341662 6 277 5887339440 2^4 * 3 * 5 * 23 * 139 * 7673 %e A341662 7 283 6414247920 2^4 * 3 * 5 * 47 * 71 * 8009 %e A341662 8 347 14498327280 2^4 * 3 * 5 * 29 * 173 * 12041 %e A341662 9 383 21517662720 2^9 * 3 * 5 * 191 * 14669 %e A341662 10 641 168823196160 2^9 * 3 * 5 * 107 * 205441 %e A341662 11 653 181824635280 2^4 * 3 * 5 * 109 * 163 * 42641 %t A341662 Select[Range[21000], PrimeQ[#] && DivisorSigma[0, #^4 - 1] == 160 &] (* _Amiram Eldar_, Feb 26 2021 *) %o A341662 (PARI) isok(p) = isprime(p) && (numdiv(p^4-1) == 160); \\ _Michel Marcus_, Feb 26 2021 %Y A341662 Cf. A000005, A000040, A309906, A341656, A341661. %K A341662 nonn %O A341662 1,1 %A A341662 _Jon E. Schoenfield_, Feb 26 2021