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A106310 Primes p such that p^2 divides some T(k), yet p does not divide any T(j) for any j<k, where T(n) is the n-th tribonacci number (A000073). +0
1
47, 617, 2693 (list; graph; listen)
OFFSET

1,1

COMMENT

No other p < 10^6. For Fibonacci numbers, A000045, there are no known primes with this property.

EXAMPLE

47 is here because the 29th tribonacci number, 15902591, is the first tribonacci number divisible by 47 and 47^2 also divides it. Similarly, 617^2 divides T(409) and 2693^2 divides T(10553).

MATHEMATICA

FibonacciZero[n_, kMax_, m_] := Module[{a, s, k}, a=Join[{1}, Table[0, {n-1}]]; a=Mod[a, m]; k=0; While[k++; s=Mod[Plus@@a, m]; a=RotateLeft[a]; a[[n]]=s; s>0&&k<kMax]; If[s==0, k, -1]]; Do[p=Prime[n]; zero=FibonacciZero[3, Infinity, p]; If[zero==FibonacciZero[3, zero, p^2], Print[{p, zero}]], {n, 1000}]

CROSSREFS

Sequence in context: A142253 A142577 A098226 this_sequence A163709 A101793 A032626

Adjacent sequences: A106307 A106308 A106309 this_sequence A106311 A106312 A106313

KEYWORD

bref,hard,more,nonn

AUTHOR

T. D. Noe (noe(AT)sspectra.com), May 17 2005

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Last modified December 15 00:47 EST 2009. Contains 170825 sequences.


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