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A065964
a(n) is the smallest k such that (k^3 + 1)/(n^3 + 1) is an integer > 1.
5
3, 5, 19, 49, 17, 26, 295, 107, 649, 153, 323, 69, 145, 719, 3151, 3841, 251, 597, 6499, 362, 8821, 10165, 3527, 1399, 2981, 836, 1063, 21169, 7289, 3254, 607, 9899, 4045, 21304, 13067, 3431, 867, 803, 57799, 9183, 1601, 27527, 6159, 26459, 10993, 20538
OFFSET
1,1
COMMENTS
a(n) exists because n^3 + 1 divides (n^3 - n^2 + 1)^3 + 1. The set S of n such a(n) = n^3 - n^2 + 1 is S = (2, 3, 4, 7, 9, 15, 16, 19, 21, 22, ...).
LINKS
MATHEMATICA
Do[k = 1; While[m = (k^3 + 1)/(n^3 + 1); m < 2 || !IntegerQ[m], k++ ]; Print[k], {n, 1, 50} ]
PROG
(PARI) { for (n=1, 300, a=n + 1; while (frac((a^3 + 1)/(n^3 + 1)), a++); write("b065964.txt", n, " ", a) ) } \\ Harry J. Smith, Nov 04 2009
CROSSREFS
Cf. A065876.
Sequence in context: A148543 A148544 A148545 * A340737 A209778 A148546
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Dec 08 2001
EXTENSIONS
Corrected and extended by Robert G. Wilson v, Dec 11 2001
STATUS
approved