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 A160524 #37 Aug 11 2025 07:25:04 %S A160524 8,15,17,37,41,46,51,53,55,65,75,77,102,106,110,116,130,131,138,140, %T A160524 147,157,158,165,166,167,178,180,183,192,197,217,222,225,233,235,251, %U A160524 258,285,287,302,310,315,321,325,328,333,336,340,355,368,371,377,380,393,416,418,420,430,432,441,447 %N A160524 Exceptional class of numbers k such that p(5k+4) == 0 (mod 25), where p() = A000041(). %C A160524 The unexceptional class consists of the numbers k == 4 (mod 5). %C A160524 (p(5*a(m) + 4)/25: m >= 1) = (3007, 553946, 1999837, 61090943985, 341143252095, 2634063438811, 18381830017947, 38993374797785, 81633034103003, ...) - _Petros Hadjicostas_, Sep 23 2019 %H A160524 Watson, G. N., <a href="https://gdz.sub.uni-goettingen.de/id/PPN243919689_0179">Ramanujans Vermutung über Zerfällungsanzahlen</a>, J. Reine Angew. Math. (Crelle) 179 (1938), 97-128; see p. 113. %p A160524 isA160524 := n -> 0 = modp(combinat:-numbpart(5*n + 4), 25) and 4 <> modp(n, 5): %p A160524 select(isA160524, [$1..200]); # _Petros Hadjicostas_, Sep 23 2019 %Y A160524 Cf. A000041, A071734, A327713, A327714. %K A160524 nonn %O A160524 1,1 %A A160524 _N. J. A. Sloane_, Nov 13 2009 %E A160524 More terms from _Petros Hadjicostas_, Sep 23 2019