%I A140090
%S A140090 0,5,13,24,38,55,75,98,124,153,185,220,258,299,343,390,440,493,549,608,
%T A140090 670,735,803,874,948,1025,1105,1188,1274,1363,1455,1550,1648,1749,1853,
%U A140090 1960,2070,2183,2299,2418,2540,2665,2793,2924
%N A140090 n(3n+7)/2.
%F A140090 a(n)=(3*n^2 + 7*n)/2.
%F A140090 a(n)=3*n+a(n-1)-1 (with a(1)=0) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), 
               Nov 08 2009]
%e A140090 For n=2, a(2)=3*2+0-1=5; n=3, a(3)=3*3+5-1=13; n=4, a(4)=3*4+13-1=24 
               [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 08 2009]
%t A140090 s=-1;lst={};Do[s+=n+n+n-1;If[s>=0, AppendTo[lst, s]], {n, 0, 6!, 1}];
               lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Nov 04 2008]
%t A140090 Table[Sum[i + n - 3, {i, 4, n}], {n, 3, 50}] [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), 
               Jul 11 2009]
%Y A140090 Cf. A000326, A005449, A045943, A115067, A140091, A059845, A140672, A140673, 
               A140674, A140675.
%Y A140090 The generalized pentagonal numbers b*n+3*n*(n-1)/2, for b = 1 through 
               12, form sequences A000326, A005449, A045943, A115067, A140090, A140091, 
               A059845, A140672, A140673, A140674, A140675, A151542.
%Y A140090 Sequence in context: A075829 A119248 A114998 this_sequence A121511 A156679 
               A004627
%Y A140090 Adjacent sequences: A140087 A140088 A140089 this_sequence A140091 A140092 
               A140093
%K A140090 easy,nonn
%O A140090 0,2
%A A140090 Omar E. Pol (info(AT)polprimos.com), May 22 2008