%I A056121
%S A056121 0,8,17,27,38,50,63,77,92,108,125,143,162,182,203,225,248,272,297,323,
%T A056121 350,378,407,437,468,500,533,567,602,638,675,713,752,792,833,875,918,
%U A056121 962,1007,1053,1100,1148,1197,1247,1298,1350,1403,1457,1512,1568,1625
%N A056121 n*(n+15)/2.
%C A056121 a(n)=A000096 + 6 * A001477, a(n)=A056119 + A001477 and a(n)=A056126 - 
               A001477 - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Oct 01 2006
%C A056121 a(n) = A126890(n,7) for n>6. - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), 
               Dec 30 2006
%F A056121 G.f.(x)=x(8-7x)/(1-x)^3.
%F A056121 a(n)=C(n,2)-7*n,n>=15 - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), 
               Nov 26 2006
%F A056121 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-1,8), for n>=1. [From Milan 
               R. Janjic (agnus(AT)blic.net), Dec 20 2008]
%F A056121 a(n)=n+a(n-1)+6 (with a(1)=0) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), 
               Nov 19 2009]
%e A056121 For n=2, a(2)=2+0+6=8; n=3, a(3)=3+8+6=17; n=4, a(4)=4+17+6=27 [From 
               Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 19 2009]
%p A056121 a:=n->sum(floor(k+2*n/(k+n)), k=7..n): seq(a(n),n=6..56); - Zerinvary 
               Lajos (zerinvarylajos(AT)yahoo.com), Oct 01 2006
%p A056121 [seq(binomial(n,2)-7*n,n=15..65)]; - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), 
               Nov 26 2006
%p A056121 seq(sum(k, k=8..n), n=7..57); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), 
               Mar 09 2008
%p A056121 a:=n->sum(numer (k/(k+3)), k=8..n): seq(a(n), n=7..57); - Zerinvary Lajos 
               (zerinvarylajos(AT)yahoo.com), May 31 2008
%p A056121 with(finance):seq(add(cashflows([2,k,5], 0 ),k=1..n),n=0..50); - Zerinvary 
               Lajos (zerinvarylajos(AT)yahoo.com), Jun 22 2008
%t A056121 i=-7;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 A056121 Cf. A056119.
%Y A056121 Cf. A000096, A056119, A056126, A056000, A001477.
%Y A056121 Sequence in context: A017257 A052222 A044441 this_sequence A028884 A099358 
               A077222
%Y A056121 Adjacent sequences: A056118 A056119 A056120 this_sequence A056122 A056123 
               A056124
%K A056121 easy,nonn,new
%O A056121 0,2
%A A056121 Barry E. Williams, Jul 06 2000
%E A056121 More terms from James A. Sellers (sellersj(AT)math.psu.edu), Jul 07 2000