%I A056119
%S A056119 0,7,15,24,34,45,57,70,84,99,115,132,150,169,189,210,232,255,279,304,
%T A056119 330,357,385,414,444,475,507,540,574,609,645,682,720,759,799,840,882,
%U A056119 925,969,1014,1060,1107,1155,1204,1254,1305,1357,1410,1464,1519,1575
%N A056119 a(n)=n*(n+13)/2.
%C A056119 a(n)=A000096 + 5 * A001477, a(n)=A056115 + A001477 and a(n)=A056121 - 
               A001477 - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Oct 01 2006
%C A056119 a(n) = A126890(n,6) for n>5. - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), 
               Dec 30 2006
%C A056119 a(n)=A000096(n) + 5 * A001477(n), a(n)=A056115(n) + A001477(n), a(n)=A056121(n) 
               - A001477(n). - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Feb 
               22 2008
%D A056119 P. Lafer, Discovering the square-triangular numbers, Fib. Quart. 9 (1971), 
               pps. 93-105.
%F A056119 G.f.(x)=x(7-6x)/(1-x)^3.
%F A056119 a(n)=C(n,2)-6*n,n>=13 - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), 
               Nov 25 2006
%F A056119 If we define f(n,i,a)=sum(binomial(n,k)*stirling1(n-k,i)*product(-a-j,
               j=0..k-1),k=0..n-i), then a(n) = -f(n,n-1,7), for n>=1. [From Milan 
               R. Janjic (agnus(AT)blic.net), Dec 20 2008]
%F A056119 a(n)=n+a(n-1)+5 (with a(1)=0) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), 
               Nov 19 2009]
%e A056119 For n=2, a(2)=2+0+5=7; n=3, a(3)=3+7+5=15; n=4, a(4)=4+15+5=24 [From 
               Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 19 2009]
%p A056119 a:=n->sum(floor(k+2*n/(k+n)), k=6..n): seq(a(n),n=5..55); - Zerinvary 
               Lajos (zerinvarylajos(AT)yahoo.com), Oct 01 2006
%p A056119 [seq(binomial(n,2)-6*n,n=13..63)]; - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), 
               Nov 25 2006
%p A056119 seq(sum(k, k=7..n), n=6..56); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), 
               Feb 22 2008
%p A056119 a:=n->sum(numer (k/(k+3)), k=7..n): seq(a(n), n=6..56); - Zerinvary Lajos 
               (zerinvarylajos(AT)yahoo.com), May 31 2008
%p A056119 with(finance):seq(add(cashflows([k, k, 12], 0 ), k=1..n)/2, n=0..45); 
               # [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Dec 22 2008]
%t A056119 i=-6;s=0;lst={};Do[s+=n+i;If[s>=0, AppendTo[lst, s]], {n, 0, 6!, 1}];
               lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Oct 29 2008]
%Y A056119 Cf. A056115.
%Y A056119 Cf. A000096, A056115, A056121, A056000, A001477.
%Y A056119 Cf. A000096, A056115, A056121.
%Y A056119 Sequence in context: A056828 A113505 A076796 this_sequence A082111 A154935 
               A012480
%Y A056119 Adjacent sequences: A056116 A056117 A056118 this_sequence A056120 A056121 
               A056122
%K A056119 easy,nonn,new
%O A056119 0,2
%A A056119 Barry E. Williams, Jul 04 2000
%E A056119 More terms from James A. Sellers (sellersj(AT)math.psu.edu), Jul 05 2000