cp's OEIS Frontend

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.

A219795 Sum of the absolute values of the antidiagonals of the triangle A135929(n) companion. See the comment.

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%I A219795 #9 Jan 06 2013 15:19:07
%S A219795 2,2,2,2,3,3,5,7,10,11,16,23,33,44,58,81,114,158,212,293,407,565,777,
%T A219795 1064,1471,2036,2813,3863,5334,7370,10183,14046,19356,26726,36909,
%U A219795 50955,70251,96977,133886,184841,255092
%N A219795 Sum of the absolute values of the antidiagonals of the triangle A135929(n) companion. See the comment.
%C A219795 The companion to A135929(n) is the triangle
%C A219795 2;
%C A219795 2, 0;
%C A219795 2, 0,  1;
%C A219795 2, 0, -1, 0;
%C A219795 2, 0, -3, 0, -1;
%C A219795 2, 0, -5, 0,  0, 0;
%C A219795 2, 0, -7, 0,  3, 0, 1;
%C A219795 2, 0, -9, 0,  8, 0, 1, 0;
%C A219795 (A192011(n) beginning with 2 instead of -1).
%C A219795 Consider a(1),a(5),a(10),a(14), that is, a(A193910(n) -1).
%C A219795 a(1)+a(4)-a(5) = 2, a(5)+a(8)-a(9) = 2, a(10)+a(13)-a(14) = 2, a(14)+a(17)-a(18) = 4, a(19)+a(22)-a(23) = 6, a(23)+a(26)-a(27) = 14, yields 2,2,2,4,6,14,24,60,... = 2*A047749(n) or 2, followed with A116637(n+1).
%F A219795 a(n) = sum abs ( [k=0..floor(n/2)] A192011(n-k,k) ), a(0)=2.
%e A219795 a(0)=2, a(1)=2, a(2)=2+0, a(3)=2+0, a(4)=2+0+1, a(5)=2+0+1.
%p A219795 A219795 := proc(n)
%p A219795     if n=0 then
%p A219795         2;
%p A219795     else
%p A219795         add(abs(A192011(n-k,k)),k=0..floor(n/2)) ;
%p A219795     end if;
%p A219795 end proc: # _R. J. Mathar_, Jan 06 2013
%K A219795 nonn
%O A219795 0,1
%A A219795 _Paul Curtz_, Nov 28 2012
%E A219795 a(24)-a(40) from Jean-Francois Alcover, Nov 28 2012