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%I #21 Aug 23 2022 14:45:15
%S 0,1,19,200,1320,6230,23086,71484,192900,467115,1036585,2140996,
%T 4164524,7698600,13623260,23210440,38252856,61222389,95462175,
%U 145416880,216905920,317444666,456618954,646518500,902235100,1242431775,1689989301,2272736844
%N P(P(n))-P(P(n-1)), where P(n) = n(n+1)(n+2)/6 (cf. A000292).
%F From _Chai Wah Wu_, May 28 2016 : (Start)
%F a(n) = 9*a(n-1) - 36*a(n-2) + 84*a(n-3) - 126*a(n-4) + 126*a(n-5) - 84*a(n-6) + 36*a(n-7) - 9*a(n-8) + a(n-9)
%F G.f.: x*(4*x^5 + 80*x^4 + 120*x^3 + 65*x^2 + 10*x + 1)/(1 - x)^9 (End)
%o (PARI) P(n) = n*(n+1)*(n+2)/6;
%o a(n) = P(P(n)) - P(P(n-1)); \\ _Michel Marcus_, Sep 16 2013
%Y Cf. A000292, A111400.
%K easy,nonn
%O 0,3
%A _Amarnath Murthy_, Nov 07 2005
%E Better description from _Jonathan Vos Post_, Nov 11 2005
%E Edited by _N. J. A. Sloane_, Nov 11, 2005
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