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A093500 a(n) = (15*n^2 + 5*n + 2)/2. 2
11, 36, 76, 131, 201, 286, 386, 501, 631, 776, 936, 1111, 1301, 1506, 1726, 1961, 2211, 2476, 2756, 3051, 3361, 3686, 4026, 4381, 4751, 5136, 5536, 5951, 6381, 6826, 7286, 7761, 8251, 8756, 9276, 9811, 10361, 10926, 11506, 12101, 12711, 13336, 13976 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Icosahedral gnomic numbers: first differences of icosahedral numbers.
The sequence is related to other gnomons of polyhedra, known by other more familiar names: triangular (tetrahedral gnomic), hex (cubic gnomic), square pyramidal numbers (octahedral gnomic).
LINKS
FORMULA
a(n) = 3*a(n-1)-3*a(n-2)+a(n-3). G.f.: x*(11+3*x+x^2)/(1-x)^3. - Colin Barker, Apr 30 2012
MATHEMATICA
Table[(15n^2+5n+2)/2, {n, 50}] (* Harvey P. Dale, Jun 28 2014 *)
PROG
(Magma) [(15*n^2+5*n+2)/2: n in [1..50]]; // Vincenzo Librandi, Aug 16 2011
(PARI) a(n)=(15*n^2+5*n+2)/2 \\ Charles R Greathouse IV, Jun 16 2017
CROSSREFS
Sequence in context: A044088 A044469 A015246 * A081438 A160483 A034309
KEYWORD
easy,nonn
AUTHOR
Michael Joseph Halm, May 13 2004
EXTENSIONS
New definition from Ralf Stephan, Dec 01 2004
Name corrected by Arkadiusz Wesolowski, Aug 15 2011
STATUS
approved

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Last modified March 19 06:25 EDT 2024. Contains 370953 sequences. (Running on oeis4.)