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 A276971 #13 Oct 12 2018 15:31:33 %S A276971 1,3,11,15,31,35,51,121,341,451,455,671,781,1111,1235,1271,1441,1547, %T A276971 1661,1991,2091,2101,2321,2651,2761,2981,3091,3421,3641,3731,3751, %U A276971 4403,4411,4631,4741,5071,5401,5731,5951,6171,6191,6281,6611,6851,6941,7051,7271,7601,7711,8261,8371,8435,8921 %N A276971 Odd integers n such that 2^n == 2^11 (mod n). %C A276971 Also, integers n such that 2^(n-11) == 1 (mod n). %C A276971 For all m, 2^A128124(m)-1 belongs to this sequence. %H A276971 Seiichi Manyama, <a href="/A276971/b276971.txt">Table of n, a(n) for n = 1..10000</a> %t A276971 m = 2^11; Join[Select[Range[1, m, 2], Divisible[2^# - m, #] &], %t A276971 Select[Range[m + 1, 10^6, 2], PowerMod[2, #, #] == m &]] (* _Robert Price_, Oct 12 2018 *) %Y A276971 The odd terms of A015935. %Y A276971 Odd integers n such that 2^n == 2^k (mod n): A176997 (k=1), A173572 (k=2), A276967 (k=3), A033984 (k=4), A276968 (k=5), A215610 (k=6), A276969 (k=7), A215611 (k=8), A276970 (k=9), A215612 (k=10), this sequence (k=11), A215613 (k=12). %Y A276971 Cf. A128124. %K A276971 nonn,easy %O A276971 1,2 %A A276971 _Max Alekseyev_, Sep 22 2016