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%I #22 Sep 08 2022 08:45:39
%S 0,7,49,126,238,385,567,784,1036,1323,1645,2002,2394,2821,3283,3780,
%T 4312,4879,5481,6118,6790,7497,8239,9016,9828,10675,11557,12474,13426,
%U 14413,15435,16492,17584,18711,19873,21070,22302,23569
%N 7 times heptagonal numbers: 7*n*(5*n-3)/2.
%C 7 times 7-gonal numbers.
%H Ivan Panchenko, <a href="/A152777/b152777.txt">Table of n, a(n) for n = 0..1000</a>
%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F a(n) = (35*n^2 - 21*n)/2 = A000566(n)*7.
%F a(n) = a(n-1)+35*n-28 (with a(0)=0). - _Vincenzo Librandi_, Dec 15 2010
%p A152777:=n->(35*n^2 - 21*n)/2; seq(A152777(n), n=0..100); # _Wesley Ivan Hurt_, Mar 04 2014
%t s=0;lst={s};Do[s+=n;AppendTo[lst,s],{n,7,8!,35}];lst (* _Vladimir Joseph Stephan Orlovsky_, Apr 03 2009 *)
%o (Magma) [ 7*n*(5*n-3)/2 : n in [0..50] ]; // _Wesley Ivan Hurt_, Jun 09 2014
%o (PARI) a(n)=7*n*(5*n-3)/2 \\ _Charles R Greathouse IV_, Jun 17 2017
%Y Cf. A000566.
%K easy,nonn
%O 0,2
%A _Omar E. Pol_, Dec 13 2008
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