OFFSET
0,2
COMMENTS
Never prime, as a(n) = (2n^2 + 2n + 1) * (n^8 + 4n^7 + 18n^6 + 40n^5 + 56n^4 + 50n^3 + 27n^2 + 8n + 1), multiple of A001844(n). Semiprime for n in {2, 4, 7, 14, 19, 22, 32, 60, 65, 70, 87, 99, 102, 135, 137, ...}. - Jonathan Vos Post, Aug 26 2011
REFERENCES
B. K. Teo and N. J. A. Sloane, Magic numbers in polygonal and polyhedral clusters, Inorgan. Chem. 24 (1985), 4545-4558.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..10000
FORMULA
G.f.: -(x^8 + 1012*x^7 + 46828*x^6 + 408364*x^5 + 901990*x^4 + 408364*x^3 + 46828*x^2 + 1012*x + 1)*(1+x)^2 / (x-1)^11. - R. J. Mathar, Aug 27 2011
MATHEMATICA
Total/@Partition[Range[0, 20]^10, 2, 1] (* Harvey P. Dale, Aug 04 2019 *)
PROG
(Magma) [(n+1)^10+n^10: n in [0..20]]; // Vincenzo Librandi, Aug 27 2011
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved