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 A257805 #5 May 13 2015 15:43:57 %S A257805 1,0,0,-1,-2,-5,-6,-12,-20,-30,-37,-41,-39,-37,-51,-141,-459,-1355, %T A257805 -3521,-8212,-17510,-34685,-64692,-114953,-196617,-326254,-527227, %U A257805 -828432,-1254932,-1800115,-2361626,-2613748,-1777205,1765725,11078200,31587185,72445272,148564309,283768148,516004565,906713910,1559424960,2660917133,4581930804,8140743021,15311144248,31111188060,68512065476 %N A257805 Partial sums of A257259: a(0) = 1; for n >= 1, a(n) = A257259(n) + a(n-1). %F A257805 a(0) = 1; for n >= 1, a(n) = A257259(n) + A257805(n-1). %F A257805 Other identities. For all n >= 0: %F A257805 a(n) = -A257806(A218600(n+1)). %o A257805 (Scheme, with memoization-macro definec) %o A257805 (definec (A257805 n) (if (zero? n) 1 (+ (A257259 n) (A257805 (- n 1))))) %o A257805 ;; Alternative implementation: %o A257805 (define (A257805 n) (- (A257806 (A218600 (+ 1 n))))) %Y A257805 Cf. A218600, A257259, A257806. %Y A257805 Cf. also A218542, A218543 and A218789. %K A257805 sign %O A257805 0,5 %A A257805 _Antti Karttunen_, May 13 2015