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 A261235 #11 Aug 17 2015 09:49:03 %S A261235 1,3,7,17,45,122,334,915,2511,6906,19039,52691,146641,410734,1157321, %T A261235 3276419,9307640,26509145,75669108,216483760,620847130,1784898316, %U A261235 5143127022,14847548759,42923323624,124213679008,359730306331,1042521363580,3023562595587,8776718908896,25502164336020,74179903571807,216005883269160,629644927525768,1837129499003121,5364782084798156 %N A261235 First differences of A261234. %F A261235 a(n) = A261234(n+1) - A261234(n). %o A261235 (Scheme) (define (A261235 n) (- (A261234 (+ 1 n)) (A261234 n))) %Y A261235 Cf. A261234. %Y A261235 Cf. also A226060. %K A261235 nonn %O A261235 0,2 %A A261235 _Antti Karttunen_, Aug 13 2015 %E A261235 Terms from a(23) onward computed from the output of _Hiroaki Yamanouchi_'s program (given in A261234) by _Antti Karttunen_, Aug 16 2015