

A109347


Zsigmondy numbers for a = 5, b = 3: Zs(n, 5, 3) is the greatest divisor of 5^n  3^n (A005058) that is relatively prime to 5^m  3^m for all positive integers m < n.


9



2, 1, 49, 17, 1441, 19, 37969, 353, 19729, 421, 24325489, 481, 609554401, 10039, 216001, 198593, 381405156481, 12979, 9536162033329, 288961, 18306583, 6125659, 5960417405949649, 346561, 103408180634401, 152787181, 3853528045489, 179655841, 93132223146359169121
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OFFSET

1,1


LINKS

Table of n, a(n) for n=1..29.
Eric Weisstein's World of Mathematics, Zsigmondy's Theorem


PROG

(PARI) rad(n) = factorback(factor(n)[, 1])
lista(nn) = {prad = 1; for (n=1, nn, val = 5^n3^n; d = divisors(val); gd = 1; forstep(k=#d, 1, 1, if (gcd(d[k], prad) == 1, g = d[k]; break)); print1(g, ", "); prad = ra(prad*val); ); } \\ Michel Marcus, Nov 15 2016


CROSSREFS

Cf. A064078, A064079, A064080, A064081, A064082, A064083, A109325, A109348, A109349.
Sequence in context: A100018 A255856 A037056 * A054210 A225778 A271442
Adjacent sequences: A109344 A109345 A109346 * A109348 A109349 A109350


KEYWORD

nonn


AUTHOR

Jonathan Vos Post, Aug 21 2005


EXTENSIONS

Edited, corrected and extended by Ray Chandler, Aug 26 2005
Definition corrected by Jerry Metzger, Nov 04 2009
More terms from Michel Marcus, Nov 14 2016


STATUS

approved



