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 A036096 Centered cube numbers: (n+1)^18 + n^18. 3
 1, 262145, 387682633, 69106897225, 3883416742361, 105374653934041, 1729973554578865, 19642812107392433, 168109033806481105, 1150094635296999121, 6559917313492231481, 32183250594377475385 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Never prime nor semiprime, as a(n) = (2n^2 + 2n +1) * (n^4 + 2n^3 + 5n^2 + 4n +1) * (n^12 + 6n^11 + 51n^10 + 200n^9 + 480n^8 + 786n^7 + 923n^6 + 792n^5 + 495n^4 + 220n^3 + 66n^2 + 12n + 1). Triprime for n in {9, 347, 1069, 1072, ...}. - Jonathan Vos Post, Aug 27 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 EXAMPLE 9^18 + (9+1)^18 = 1150094635296999121 = 181 * 8461 * 750988536481, the minimum nontrivial number of prime factors. MATHEMATICA Total/@Partition[Range[0, 20]^18, 2, 1] (* Harvey P. Dale, May 10 2022 *) PROG (Magma) [(n+1)^18+n^18: n in [0..20]]; // Vincenzo Librandi, Aug 28 2011 (PARI) a(n)=(n+1)^18+n^18 \\ Charles R Greathouse IV, Aug 30 2017 CROSSREFS Cf. A010806, A036094, A036095. Sequence in context: A352984 A017699 A013966 * A170792 A170801 A340907 Adjacent sequences: A036093 A036094 A036095 * A036097 A036098 A036099 KEYWORD nonn,easy AUTHOR N. J. A. Sloane STATUS approved

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Last modified July 17 10:03 EDT 2024. Contains 374375 sequences. (Running on oeis4.)