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 A007158 M1995 #17 Jul 08 2025 17:01:53
%S A007158 2,10,3866,297538923922,675089708540070294583609203589639922,
%T A007158 202089899117162771494026986677587201812698520846319037282893739002965043831824039051995734327796615178840634970
%N A007158 Essentially n-ary operations in a certain 3-element algebra.
%D A007158 J. Berman, ``Free spectra of 3-element algebras,'' in R. S. Freese and O. C. Garcia, editors, Universal Algebra and Lattice Theory (Puebla, 1982), Lect. Notes Math. Vol. 1004, 1983.
%D A007158 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A007158 J. Berman, <a href="/A007153/a007153.pdf">Free spectra of 3-element algebras</a>, R. S. Freese and O. C. Garcia, editors, Universal Algebra and Lattice Theory (Puebla, 1982), Lect. Notes Math. Vol. 1004, 1983. (Annotated scanned copy)
%F A007158 a(n) = Sum_{i=0..n} (-1)^(n-i) * binomial(n, i) * A007155(i). - _Sean A. Irvine_, Nov 05 2017
%Y A007158 Cf. A007155.
%K A007158 nonn
%O A007158 0,1
%A A007158 _N. J. A. Sloane_
%E A007158 a(5) from _Sean A. Irvine_, Nov 05 2017