%I A062123
%S A062123 2,11,29,56,92,137,191,254,326,407,497,596,704,821,947,1082,1226,1379,
%T A062123 1541,1712,1892,2081,2279,2486,2702,2927,3161,3404,3656,3917,4187,4466,
%U A062123 4754,5051,5357,5672,5996,6329,6671,7022,7382,7751,8129,8516,8912,9317
%N A062123 2 + (n + n^2)*9/2.
%C A062123 Third column of A046741.
%C A062123 Except for the first term, a(n)=9*n+a(n-1), (with a(1)=11) [From Vincenzo 
               Librandi (vincenzo.librandi(AT)tin.it), Oct 24 2009]
%D A062123 I. P. Goulden and D. M. Jackson, Combinatorial Enumeration, Wiley, N.Y., 
               1983,(2.3.14).
%H A062123 Harry J. Smith, <a href="b062123.txt">Table of n, a(n) for n=0,...,1000</
               a>
%F A062123 G.f.: (1+2*x)*(2+x)/(1-x)^3. Generally, g.f. for k-th column of A046741 
               is coefficient of y^k in expansion of (1-y)/((1-y-y^2)*(1-y)-(1+y)*x).
%F A062123 a(n)=9*n+a(n-1)-9 (with a(1)=2) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), 
               Nov 18 2009]
%e A062123 For n=2, a(2)=9*2+2-9=11: n=3, a(3)=9*3+11-9=29; n=4, a(4)=9*4+29-9=56 
               [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 18 2009]
%o A062123 (PARI) { for (n=0, 1000, write("b062123.txt", n, " ", 2 + (n + n^2)*9/
               2) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Aug 02 2009]
%Y A062123 Cf. dumbbells: A002940, A002941, A002889, A046741, A055608, A062124-A062127.
%Y A062123 Sequence in context: A090389 A061238 A046500 this_sequence A117560 A024178 
               A009312
%Y A062123 Adjacent sequences: A062120 A062121 A062122 this_sequence A062124 A062125 
               A062126
%K A062123 easy,nonn
%O A062123 0,1
%A A062123 Vladeta Jovovic (vladeta(AT)eunet.rs), Jun 04 2001
%E A062123 More terms from Larry Reeves (larryr(AT)acm.org), Jun 06 2001