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 A218220 #10 Apr 27 2024 17:22:02 %S A218220 1,1,1,1,1,-1,1,1,0,-1,1,1,1,-1,1,1,1,2,1,-1,1,1,1,3,5,1,0,-1,1,1,4, %T A218220 11,13,1,1,-1,1,1,5,19,41,34,1,1,1,1,1,6,29,91,153,89,1,0,1,1,1,7,41, %U A218220 169,436,571,233,1,-1,-1,1,1,8,55,281,985,2089,2131,610,1,-1,-1,1,1,9,71,433,1926,5741,10009,7953,1597,1,0,1,1,1,10,89,631,3409,13201,33461,47956,29681 %N A218220 Array a(n,m) read by antidiagonals where a(0,m)=a(1,m)=1 and a(n,m) = m*a(n-1,m)-a(n-2,m) for n>=2. %C A218220 Variant of A094954 and A162997. %C A218220 a(n,0) alternates 1,1,-1,-1,1,1,... %C A218220 a(n,1) alternates 1,1,0,-1,-1,0,... %C A218220 a(n,2)=1 %C A218220 a(n,3) is alternating Fibonacci numbers. %e A218220 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,... %e A218220 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,... %e A218220 -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,... %e A218220 -1, -1, 1, 5, 11, 19, 29, 41, 55, 71, 89,... %e A218220 1, -1, 1, 13, 41, 91, 169, 281, 433, 631, 881,... %e A218220 1, 0, 1, 34, 153, 436, 985,1926,3409,5608,8721,... %e A218220 -1, 1, 1, 89, 571,2089,5741,13201,26839,49841,86329,... %e A218220 -1, 1, 1, 233,2131,10009,33461,90481,211303,442961,854569,... %Y A218220 Cf. A218219. %K A218220 sign,tabl,easy %O A218220 0,18 %A A218220 _Nico Brown_, Oct 23 2012