OFFSET
0,3
COMMENTS
See comments in A255184.
REFERENCES
E. Deza and M. M. Deza, Figurate numbers, World Scientific Publishing (2012), page 6 (27th row of the table).
LINKS
Luciano Ancora, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (3,-3,1).
FORMULA
G.f.: x*(-1 - 26*x)/(-1 + x)^3.
Product_{n>=2} (1 - 1/a(n)) = 27/29. - Amiram Eldar, Jan 22 2021
E.g.f.: exp(x)*(x + 27*x^2/2). - Nikolaos Pantelidis, Feb 06 2023
MATHEMATICA
Table[n (27 n - 25)/2, {n, 40}]
PolygonalNumber[29, Range[0, 40]] (* Harvey P. Dale, Jul 25 2021 *)
PROG
(PARI) a(n)=n*(27*n-25)/2 \\ Charles R Greathouse IV, Jun 17 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Luciano Ancora, Apr 04 2015
STATUS
approved