A164015 5 times centered pentagonal numbers: 5*(5*n^2 + 5*n + 2)/2.
5, 30, 80, 155, 255, 380, 530, 705, 905, 1130, 1380, 1655, 1955, 2280, 2630, 3005, 3405, 3830, 4280, 4755, 5255, 5780, 6330, 6905, 7505, 8130, 8780, 9455, 10155, 10880, 11630, 12405, 13205, 14030, 14880, 15755, 16655, 17580, 18530
Offset: 0
Links
- Ivan Panchenko, Table of n, a(n) for n = 0..1000
- Index entries for linear recurrences with constant coefficients, signature (3,-3,1).
Programs
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Mathematica
Table[5(5n^2+5n+2)/2,{n,0,40}] (* or *) LinearRecurrence[{3,-3,1},{5,30,80},40] (* Harvey P. Dale, Oct 08 2011 *) -
PARI
a(n)=25*n*(n+1)/2+5 \\ Charles R Greathouse IV, Jul 17 2011
Formula
a(n) = 5*A005891(n).
a(n) = a(n-1) + 25*n (with a(0)=5). - Vincenzo Librandi, Nov 30 2010
a(0)=5, a(1)=30, a(2)=80, a(n) = 3*a(n-1)-3*a(n-2)+a(n-3). - Harvey P. Dale, Oct 08 2011
G.f.: (5*(x*(x+3)+1))/(1-x)^3. - Harvey P. Dale, Oct 08 2011
E.g.f.: (5/2)*(2 + 10*x + 5*x^2)*exp(x). - G. C. Greubel, Sep 06 2017