OFFSET
2,1
COMMENTS
Let s=(M-1)/(2*p) and z is multiplicative order of 3 modulo M, then M|2^(x+p*i)+3^(s+z*j), where integer i,j>=0.
PROG
(PARI)
A000043=[2, 3, 5, 7, 13, 17, 19, 31, 61, 89, 107, 127, 521, 607, 1279, 2203, 2281, 3217, 4253, 4423, 9689, 9941, 11213, 19937, 21701, 23209, 44497, 86243, 110503, 132049, 216091, 756839, 859433, 1257787, 1398269, 2976221, 3021377, 6972593, 13466917, 20996011, 24036583, 25964951, 30402457, 32582657];
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Dmitry Ezhov, Nov 28 2016
STATUS
approved