Search: id:A033580
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%I A033580
%S A033580 0,8,28,60,104,160,228,308,400,504,620,748,888,1040,1204,
%T A033580 1380,1568,1768,1980,2204,2440,2688,2948,3220,3504,3800,
%U A033580 4108,4428,4760,5104,5460,5828,6208,6600,7004,7420,7848
%N A033580 Four times second pentagonal numbers: 2*n*(3*n+1).
%F A033580 a(n)=12*n+a(n-1)-16 (with a(1)=0) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), 
               Nov 12 2009]
%e A033580 For n=2, a(2)=12*2+0-16=8; n=3, a(3)=12*3+8-16=28; n=4, a(4)=12*4+28-16=60 
               [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 12 2009]
%t A033580 s=0;lst={s};Do[s+=n++ +8;AppendTo[lst, s], {n, 0, 8!, 12}];lst [From 
               Vladimir Orlovsky (4vladimir(AT)gmail.com), Nov 16 2008]
%Y A033580 Cf. A049451, A045945, A033579.
%Y A033580 Sequence in context: A009504 A001486 A045850 this_sequence A007331 A002408 
               A101127
%Y A033580 Adjacent sequences: A033577 A033578 A033579 this_sequence A033581 A033582 
               A033583
%K A033580 nonn,new
%O A033580 0,2
%A A033580 N. J. A. Sloane (njas(AT)research.att.com).

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