

A036085


Centered cube numbers: (n+1)^7 + n^7.


9



1, 129, 2315, 18571, 94509, 358061, 1103479, 2920695, 6880121, 14782969, 29487171, 55318979, 98580325, 168162021, 276272879, 439294831, 678774129, 1022558705, 1506091771, 2173871739, 3081088541, 4295446429, 5899183335, 7991296871, 10689987049, 14135325801
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OFFSET

0,2


COMMENTS

Never prime, as a(n) = (2n+1)*(n^6 + 3n^5 + 9n^4 + 13n^3 + 11n^2 + 5n + 1). Semiprimes in the sequence begin for n = 1, 2, 8, 9, 21, 30, 33, 53, 65, 81, 83.  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), 45454558.


LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..10000
Index entries for linear recurrences with constant coefficients, signature (8,28,56,70,56,28,8,1).


FORMULA

a(n) = A001015(n+1) + A001015(n).
G.f.: (1+x)*(x^6 + 120*x^5 + 1191*x^4 + 2416*x^3 + 1191*x^2 + 120*x + 1) / (x1)^8.  R. J. Mathar, Aug 27 2011


PROG

(MAGMA) [(n+1)^7+n^7: n in [0..30]]; // Vincenzo Librandi, Aug 27 2011
(PARI) a(n)=(n+1)^7+n^7 \\ Charles R Greathouse IV, Oct 07 2015


CROSSREFS

Cf. A100267, A154535, A100266, A152913, A194155, A194185, A194216.
Sequence in context: A013955 A294302 A221969 * A000541 A023876 A301551
Adjacent sequences: A036082 A036083 A036084 * A036086 A036087 A036088


KEYWORD

nonn,easy


AUTHOR

N. J. A. Sloane


STATUS

approved



