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 A341656 #15 Mar 04 2021 02:30:58 %S A341656 4,10,20,36,40,80,84,60,96,80,128,120,144,240,224,160,80,80,160,144, %T A341656 288,112,320,288,192,120,192,240,320,224,240,160,192,160,240,288,480, %U A341656 200,192,320,240,240,576,288,360,216,320,256,160,320,576,560,336,720,264 %N A341656 a(n) is the number of divisors of prime(n)^4 - 1. %C A341656 a(n) >= A309906(4) = 160 for n > 26. %F A341656 a(n) = A000005(A000040(n)^4 - 1). %e A341656 p = factorization %e A341656 n prime(n) p^4 - 1 of p^4 - 1 a(n) %e A341656 -- -------- --------- ------------------------------ ---- %e A341656 1 2 15 3 * 5 4 %e A341656 2 3 80 2^4 * 5 10 %e A341656 3 5 624 2^4 * 3 * 13 20 %e A341656 4 7 2400 2^5 * 3 * 5^2 36 %e A341656 5 11 14640 2^4 * 3 * 5 * 61 40 %e A341656 6 13 28560 2^4 * 3 * 5 * 7 * 17 80 %e A341656 7 17 83520 2^6 * 3^2 * 5 * 29 84 %e A341656 8 19 130320 2^4 * 3^2 * 5 * 181 60 %e A341656 9 23 279840 2^5 * 3 * 5 * 11 * 53 96 %e A341656 10 29 707280 2^4 * 3 * 5 * 7 * 421 80 %e A341656 11 31 923520 2^7 * 3 * 5 * 13 * 37 128 %e A341656 12 37 1874160 2^4 * 3^2 * 5 * 19 * 137 120 %e A341656 13 41 2825760 2^5 * 3 * 5 * 7 * 29^2 144 %e A341656 14 43 3418800 2^4 * 3 * 5^2 * 7 * 11 * 37 240 %e A341656 15 47 4879680 2^6 * 3 * 5 * 13 * 17 * 23 224 %e A341656 16 53 7890480 2^4 * 3^3 * 5 * 13 * 281 160 %e A341656 17 59 12117360 2^4 * 3 * 5 * 29 * 1741 80 %e A341656 18 61 13845840 2^4 * 3 * 5 * 31 * 1861 80 %e A341656 19 67 20151120 2^4 * 3 * 5 * 11 * 17 * 449 160 %e A341656 20 71 25411680 2^5 * 3^2 * 5 * 7 * 2521 144 %e A341656 21 73 28398240 2^5 * 3^2 * 5 * 13 * 37 * 41 288 %e A341656 22 79 38950080 2^6 * 3 * 5 * 13 * 3121 112 %e A341656 23 83 47458320 2^4 * 3 * 5 * 7 * 13 * 41 * 53 320 %e A341656 24 89 62742240 2^5 * 3^2 * 5 * 11 * 17 * 233 288 %e A341656 25 97 88529280 2^7 * 3 * 5 * 7^2 * 941 192 %e A341656 26 101 104060400 2^4 * 3 * 5^2 * 17 * 5101 120 %t A341656 a[n_] := DivisorSigma[0, Prime[n]^4 - 1]; Array[a, 50] (* _Amiram Eldar_, Feb 25 2021 *) %o A341656 (PARI) a(n) = numdiv(prime(n)^4-1); \\ _Michel Marcus_, Feb 25 2021 %o A341656 (Python) %o A341656 from sympy import prime, divisor_count %o A341656 def A341656(n): return divisor_count(prime(n)**4-1) # _Chai Wah Wu_, Feb 25 2021 %Y A341656 Cf. A000005, A000040, A309906. %K A341656 nonn %O A341656 1,1 %A A341656 _Jon E. Schoenfield_, Feb 25 2021