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A255186 27-gonal numbers: a(n) = n*(25*n-23)/2. 8
0, 1, 27, 78, 154, 255, 381, 532, 708, 909, 1135, 1386, 1662, 1963, 2289, 2640, 3016, 3417, 3843, 4294, 4770, 5271, 5797, 6348, 6924, 7525, 8151, 8802, 9478, 10179, 10905, 11656, 12432, 13233, 14059, 14910, 15786, 16687, 17613, 18564, 19540 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
COMMENTS
See comments in A255184.
REFERENCES
E. Deza and M. M. Deza, Figurate numbers, World Scientific Publishing (2012), page 6 (25th row of the table).
LINKS
FORMULA
G.f.: x*(-1 - 24*x)/(-1 + x)^3.
a(n) = A000217(n) + 24*A000217(n-1).
Product_{n>=2} (1 - 1/a(n)) = 25/27. - Amiram Eldar, Jan 22 2021
E.g.f.: exp(x)*(x + 25*x^2/2). - Nikolaos Pantelidis, Feb 06 2023
MATHEMATICA
Table[n (25 n - 23)/2, {n, 40}]
PROG
(PARI) a(n)=n*(25*n-23)/2 \\ Charles R Greathouse IV, Jun 17 2017
CROSSREFS
Cf. similar sequences listed in A255184.
Sequence in context: A044165 A044546 A217966 * A121737 A124726 A126381
KEYWORD
nonn,easy
AUTHOR
Luciano Ancora, Apr 04 2015
STATUS
approved

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Last modified March 29 10:59 EDT 2024. Contains 371277 sequences. (Running on oeis4.)