OFFSET
0,1
COMMENTS
A Lucas number can have more than one primitive factor; the primitive factors of L(22) are 43 and 307.
LINKS
T. D. Noe, Table of n, a(n) for n = 0..1000 (using Blair Kelly's data).
Mansur S. Boase, A Result About the Primes Dividing Fibonacci Numbers, The Fibonacci Quarterly, 39.5 (2001) 386.
J. Brillhart, P. L. Montgomery and R. D. Silverman, Tables of Fibonacci and Lucas factorizations, Math. Comp. 50 (1988), 251-260, S1-S15. Math. Rev. 89h:11002.
Blair Kelly, Fibonacci and Lucas Factorizations
MATHEMATICA
a=3; b=-1; prms={}; Table[c=a+b; a=b; b=c; f=First/@FactorInteger[c]; p=Complement[f, prms]; prms=Join[prms, p]; If[p=={}, 1, First[p]], {47}]
PROG
(PARI) lucas(n) = fibonacci(n+1)+fibonacci(n-1); \\ A000032
a(n) = {n++; my(v = vector(n, k, k--; lucas(k))); my(vf = vector(n, k, factor(v[k])[, 1]~)); for (k=1, n-1, vf[n] = setminus(vf[n], vf[k]); ); if (#vf[n], vecmin(vf[n]), 1); } \\ Michel Marcus, May 11 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Nov 16 2000
STATUS
approved