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 A069975 n*(16n^2-1). 0
 15, 126, 429, 1020, 1995, 3450, 5481, 8184, 11655, 15990, 21285, 27636, 35139, 43890, 53985, 65520, 78591, 93294, 109725, 127980, 148155, 170346, 194649, 221160, 249975, 281190, 314901, 351204, 390195, 431970, 476625, 524256, 574959 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Sum(n>0, 1/a(n)) = 3log(2)-2 = A016631 - 2. (Ramanujan) Conjecture: satisfies a linear recurrence having signature (4, -6, 4, -1). - Harvey P. Dale, Dec 17 2018 LINKS MATHEMATICA Table[n(16n^2-1), {n, 40}] (* Harvey P. Dale, Dec 17 2018 *) PROG (PARI) a(n) = n*(16*n^2-1); \\ Michel Marcus, Nov 25 2013 CROSSREFS Sequence in context: A171220 A071080 A193365 * A027779 A073509 A198850 Adjacent sequences:  A069972 A069973 A069974 * A069976 A069977 A069978 KEYWORD easy,nonn AUTHOR Benoit Cloitre, Apr 30 2002 STATUS approved

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Last modified February 27 09:59 EST 2020. Contains 332304 sequences. (Running on oeis4.)