Search: id:A028895
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%I A028895
%S A028895 0,5,15,30,50,75,105,140,180,225,275,330,390,455,525,600,680,765,855,
%T A028895 950,1050,1155,1265,1380,1500,1625,1755,1890,2030,2175,2325,2480,
%U A028895 2640,2805,2975,3150,3330,3515,3705,3900,4100,4305,4515,4730,4950
%N A028895 5 times triangular numbers.
%C A028895 Except for the first term, a(n)=5*n+a(n-1), (with a(1)=5) [From Vincenzo 
               Librandi (vincenzo.librandi(AT)tin.it), Oct 24 2009]
%F A028895 a(n) = 5/2*n*(n+1). G.f.: A(x) = 5*x/(1-x)^3.
%F A028895 a(n) = (5n^2 + 5n)/2 = 5n(n+1)/2 = A000217(n)*5. [From Omar E. Pol (info(AT)polprimos.com), 
               Dec 12 2008]
%F A028895 a(n)=5*n+a(n-1)-5 (with a(1)=0) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), 
               Nov 12 2009]
%e A028895 For n=2, a(2)=5*2+0-5=5; n=3, a(3)=5*3+5-5=15; n=4, a(4)=5*4+15-5=30 
               [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 12 2009]
%p A028895 [seq(5*binomial(n,2),n=1..45)]; - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), 
               Nov 24 2006
%p A028895 a:=n->sum(2*n+j, j=0..n): seq(a(n), n=0..44); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), 
               Apr 29 2007
%p A028895 with(finance):seq(add(cashflows([n, k, 0], 1 ), k=0..n)*4, n=0..45); 
               # [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Dec 22 2008]
%t A028895 s=0;lst={};Do[s+=n;AppendTo[lst, s], {n, 0, 7!, 5}];lst [From Vladimir 
               Orlovsky (4vladimir(AT)gmail.com), Nov 19 2008]
%t A028895 Table[Sum[i + 2*n - 1, {i, 2, n}], {n, 1, 45}] [From Zerinvary Lajos 
               (zerinvarylajos(AT)yahoo.com), Jul 11 2009]
%Y A028895 Cf. A005891, A046092, A028896.
%Y A028895 Cf. A000217. [From Omar E. Pol (info(AT)polprimos.com), Dec 12 2008]
%Y A028895 Sequence in context: A162525 A078905 A059160 this_sequence A010898 A048065 
               A048021
%Y A028895 Adjacent sequences: A028892 A028893 A028894 this_sequence A028896 A028897 
               A028898
%K A028895 nonn,easy
%O A028895 0,2
%A A028895 Joe Keane (jgk(AT)jgk.org)

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