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 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 (list; graph; refs; listen; history; text; internal format)
 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), 4545-4558. 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) / (x-1)^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 STATUS approved

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Last modified October 20 02:18 EDT 2019. Contains 328244 sequences. (Running on oeis4.)