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A112305
Let T(n) = A000073(n+1), n >= 1; a(n) = smallest k such that n divides T(k).
3
1, 3, 7, 4, 14, 7, 5, 7, 9, 19, 8, 7, 6, 12, 52, 15, 28, 12, 18, 31, 12, 8, 29, 7, 30, 39, 9, 12, 77, 52, 14, 15, 35, 28, 21, 12, 19, 28, 39, 31, 35, 12, 82, 8, 52, 55, 29, 64, 15, 52, 124, 39, 33, 35, 14, 12, 103, 123, 64, 52, 68, 60, 12, 15, 52, 35, 100, 28, 117
OFFSET
1,2
COMMENTS
Brenner proves that every prime divides some tribonacci number T(n). The Mathematica program computes similar sequences for any n-step Fibonacci sequence.
REFERENCES
Ed Pegg, Jr., Posting to Sequence Fan mailing list, Nov 30, 2005
LINKS
J. L. Brenner, Linear Recurrence Relations, Amer. Math. Monthly, Vol. 61 (1954), 171-173.
Eric Weisstein's World of Mathematics, Tribonacci Number.
EXAMPLE
T(1), T(2), T(3), T(4), ... are 1,1,2,4,7,13,24,...; a(3) = 7 because 3 first divides T(7) = A000073(8) = 24.
MATHEMATICA
n=3; Table[a=Join[{1}, Table[0, {n-1}]]; k=0; While[k++; s=Mod[Plus@@a, i]; a=RotateLeft[a]; a[[n]]=s; s!=0]; k, {i, 100}] (* T. D. Noe *)
CROSSREFS
Cf. A000073.
Cf. A112312 (least k such that prime(n) divides T(k)).
Sequence in context: A216627 A355927 A365724 * A231396 A231463 A218616
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Nov 30 2005
STATUS
approved