%I A140673
%S A140673 0,9,21,36,54,75,99,126,156,189,225,264,306,351,399,450,504,561,621,684,
%T A140673 750,819,891,966,1044,1125,1209,1296,1386,1479,1575,1674,1776,1881,1989,
%U A140673 2100,2214,2331,2451,2574,2700,2829,2961,3096
%N A140673 3n(n+5)/2.
%F A140673 a(n) = A055998(n)*3 = (3*n^2 + 15*n)/2 = n(3n+15)/2.
%F A140673 a(n)=3*n+a(n-1)+3 (with a(1)=0) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), 
               Nov 08 2009]
%e A140673 For n=2, a(2)=3*2+0+3=9; n=3, a(3)=3*3+9+3=21; n=4, a(4)=3*4+21+3=36 
               [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 08 2009]
%t A140673 lst={};Do[AppendTo[lst, 3*n*(n+5)/2], {n, 0, 6!}];lst [From Vladimir 
               Orlovsky (4vladimir(AT)gmail.com), Nov 06 2008]
%t A140673 Table[Sum[i + n - 3, {i, 6, n}], {n, 5, 52}] [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), 
               Jul 11 2009]
%Y A140673 Cf. A000326, A005449, A045943, A115067, A140090, A140091, A059845, A140672, 
               A140674, A140675, A055998.
%Y A140673 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 A140673 Sequence in context: A043112 A043892 A146069 this_sequence A059993 A036704 
               A107890
%Y A140673 Adjacent sequences: A140670 A140671 A140672 this_sequence A140674 A140675 
               A140676
%K A140673 easy,nonn
%O A140673 0,2
%A A140673 Omar E. Pol (info(AT)polprimos.com), May 22 2008