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 A277370 #38 Dec 27 2024 02:56:10 %S A277370 1,3,15,69,2155,34073,876047637,97090036327,420397381695, %T A277370 2125899832395,3177544777277,34434175473881,40845965389135, %U A277370 7267074621260963,11720938824295035,21419515204636141 %N A277370 Positive integers k that divide 7^k + 2. %C A277370 All terms are odd. %C A277370 Some larger terms: 5623143546839445899891, 46186634668308298262543001. - _Max Alekseyev_, Oct 18 2016 %F A277370 A066438(a(n)) = a(n) - 2 for n > 1. %e A277370 7^3 + 2 = 345 = 3 * 115, so 3 is a term. %t A277370 Select[Range[1, 9999, 2], Divisible[7^# + 2, #] &] (* _Alonso del Arte_, Oct 11 2016 *) %o A277370 (PARI) is(n) = Mod(7, n)^n==-2 \\ _Felix Fröhlich_, Oct 14 2016 %Y A277370 Cf. A066438. %Y A277370 Cf. Solutions to 7^n == k (mod n): A277371 (k=-3), this sequence (k=-2), A015954 (k=-1), A067947 (k=1), A277401 (k=2), A277554 (k=3). %K A277370 nonn,more %O A277370 1,2 %A A277370 _Seiichi Manyama_, Oct 11 2016 %E A277370 a(8)-a(13) from _Max Alekseyev_, Oct 18 2016 %E A277370 a(14)-a(16) from _Max Alekseyev_, Dec 27 2024