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A336117
Primes of the form q*2^h + 1, where q is a Mersenne prime.
2
7, 13, 29, 97, 113, 193, 449, 509, 769, 7937, 12289, 114689, 520193, 786433, 7340033, 8388593, 33292289, 33550337, 469762049, 2130706433, 3221225473, 8588886017, 137438691329, 206158430209, 2199023254529, 6597069766657, 562948879679489, 7881299347898369, 9007182074871809
OFFSET
1,1
FORMULA
For all n >= 1, A335885(a(n)) <= 2.
PROG
(PARI)
A000265(n) = (n>>valuation(n, 2));
isA000668(n) = (isprime(n)&&!bitand(n, 1+n));
isA336117(n) = (isprime(n)&&isA000668(A000265(n-1)));
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jul 09 2020
EXTENSIONS
More terms from Jinyuan Wang, Jul 11 2020
STATUS
approved