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 A272883 #22 Jun 20 2025 16:50:15
%S A272883 2,11,16,19,22,23,25,27,29,34,35,37,41,43,45,46,47,49,51,52,53,55,58,
%T A272883 59,61,64,66,67,69,70,71,75,76,77,79,81,83,86,87,88,89,92,94,95,97,99,
%U A272883 100,101,103,105,106,107,109,111,113,115,116,117,118,119,123,125
%N A272883 Numbers m such that sigma_k(x) = m has no solution for any k > 0.
%C A272883 Recall that sigma_k(n) = Sum_{d|n} d^k.
%C A272883 Sigma_0(n), the number of divisors of n, can be any positive integer and so is ignored in this sequence.
%C A272883 Complement of A211347.
%C A272883 Numbers n such that A271606(n) = 0.
%H A272883 Amiram Eldar, <a href="/A272883/b272883.txt">Table of n, a(n) for n = 1..10000</a>
%o A272883 (Magma) [n: n in [1..2^7] | [n] notsubset Set(Sort([DivisorSigma(k,n): n in [1..2^7+1], k in [1..2^7+1] | DivisorSigma(k,n) lt 2^7+1]))];
%Y A272883 Cf. Sequences of sigma_k(n) for k=0-24: A000005 (k=0), A000203 (k=1), A001157-A001160 (k=2-5), A013954-A013972 (k=6-24).
%Y A272883 Cf. A211347, A271606.
%K A272883 nonn
%O A272883 1,1
%A A272883 _Jaroslav Krizek_, May 08 2016