

A083734


Pseudoprimes to bases 3 and 5.


2



1541, 1729, 1891, 2821, 6601, 8911, 15841, 29341, 41041, 46657, 52633, 63973, 75361, 88831, 101101, 112141, 115921, 126217, 146611, 162401, 172081, 188461, 218791, 252601, 294409, 314821, 334153, 340561, 342271, 399001, 410041, 416641
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OFFSET

1,1


LINKS

Amiram Eldar, Table of n, a(n) for n = 1..15806 (terms 1..147 from R. J. Mathar)
F. Richman, Primality testing with Fermat's little theorem


FORMULA

a(n) = nth positive integer k(>1) such that 3^(k1) = 1 (mod k) and 5^(k1) = 1 (mod k).


EXAMPLE

a(1)=1541 since it is the first nonprime number such that 3^(k1) = 1 (mod k) and 5^(k1) = 1 (mod k).  clarified by Harvey P. Dale, Jan 29 2013


MATHEMATICA

Select[Range[420000], !PrimeQ[#]&&PowerMod[3, #1, #]==PowerMod[5, #1, #]==1&] (* Harvey P. Dale, Jan 29 2013 *)


CROSSREFS

Intersection of A005935 and A005936.
Sequence in context: A200429 A092717 A203134 * A137598 A252966 A133560
Adjacent sequences: A083731 A083732 A083733 * A083735 A083736 A083737


KEYWORD

easy,nonn


AUTHOR

Serhat Sevki Dincer (sevki(AT)ug.bilkent.edu.tr), May 05 2003


STATUS

approved



