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 A383288 #10 May 15 2025 08:18:02 %S A383288 1,7,9,11,12,13,15,16,17,19,20,23,25,29,31,37,41,43,47,49,53,59,61,63, %T A383288 67,71,73,77,79,81,83,84,89,91,97,99,101,103,105,107,108,109,112,113, %U A383288 117,119,121,127,131,132,133,135,137,139,140,143,144,149,151,153,156,157,161,163,165,167,169,171,173,175,176 %N A383288 Numbers k for which A276075(k) is a multiple of 4, where A276075 is fully additive with a(p) = PrimePi(p)!. %C A383288 All primes > 5 are included. %H A383288 Antti Karttunen, <a href="/A383288/b383288.txt">Table of n, a(n) for n = 1..20000</a> %H A383288 <a href="/index/Fa#facbase">Index entries for sequences related to factorial base representation</a>. %H A383288 <a href="/index/Pri#prime_indices">Index entries for sequences related to prime indices in the factorization of n</a>. %e A383288 7 = prime(4), and because 4 divides 24 (= 4!), 7 is present. %e A383288 9 = prime(2)*prime(2), and because 4 divides 2! + 2! = 4, 9 is present. %o A383288 (PARI) isA383288 = A383287; %Y A383288 Cf. A276075, A383287 (characteristic function). %Y A383288 Cf. also A339746, A369002. %K A383288 nonn %O A383288 1,2 %A A383288 _Antti Karttunen_, May 15 2025