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 A002735 M3486 N1417 #31 Feb 03 2025 07:21:23
%S A002735 4,14,56,331,1324,12284,49136,663061,2652244,49164554,196658216,
%T A002735 4798037791,19192151164,596372040824,2385488163296,91991577140521,
%U A002735 367966308562084,17244625801225094,68978503204900376,3861296322290987251
%N A002735 Related to Euler numbers, expansion of e.g.f. sec(x)*tan^2(x).
%D A002735 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
%D A002735 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A002735 C. Krishnamachary and M. Bheemasena Rao, <a href="/A000108/a000108_10.pdf">Determinants whose elements are Eulerian, prepared Bernoullian and other numbers</a>, J. Indian Math. Soc., 14 (1922), 55-62, 122-138 and 143-146. See p. 146. [Annotated scanned copy]
%F A002735 a(n) = b(2,n) where b(m,1) = m^2, b(m,2*n) = Sum_{k=1..m+1} b(k,2*n-1), b(m,2*n+1) = m^2 * b(m, 2*n). Note, A000364(n) = b(1, 2*n). - _Sean A. Irvine_, Sep 25 2015
%F A002735 a(2n) = A060075(n). Conjecture a(2n+1)=4*a(2n). - _R. J. Mathar_, Feb 03 2025
%Y A002735 Cf. A000364, A259688.
%K A002735 nonn
%O A002735 1,1
%A A002735 _N. J. A. Sloane_
%E A002735 More terms from _Sean A. Irvine_, Sep 25 2015