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A036085
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Centered cube numbers: (n+1)^7+n^7.
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8
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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; internal format)
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OFFSET
| 0,2
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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
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REFERENCES
| B. K. Teo and N. J. A. Sloane, Magic numbers in polygonal and polyhedral clusters, Inorgan. Chem. 24 (1985), 4545-4558.
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LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 0..10000
Index to sequences with linear recurrences with constant coefficients, signature (8,-28,56,-70,56,-28,8,-1).
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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
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PROG
| (MAGMA) [(n+1)^7+n^7: n in [0..30]]; // Vincenzo Librandi, Aug 27 2011
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CROSSREFS
| Cf. A100267, A154535, A100266, A152913, A194155, A194185, A194216.
Sequence in context: A034681 A017677 A013955 * A000541 A023876 A189608
Adjacent sequences: A036082 A036083 A036084 * A036086 A036087 A036088
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KEYWORD
| nonn,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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