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A192992
Odd n > 1 such that n+1 is a semiprime times a power of two.
1
7, 11, 15, 17, 19, 23, 27, 29, 31, 35, 39, 41, 43, 47, 49, 51, 55, 59, 63, 65, 67, 69, 71, 75, 77, 79, 83, 87, 91, 95, 97, 99, 101, 103, 109, 111, 113, 115, 119, 123, 127, 129, 131, 135, 137, 139, 143, 147, 151, 153, 155, 159, 163, 167, 169, 171, 173, 175
OFFSET
1,1
COMMENTS
Odd n such that n+1 is in A192991.
This is to thin numbers A192868 as semiprimes A001358 are to primes A000040.
FORMULA
a(n) = A192991(n) - 1.
EXAMPLE
239 is in the sequence because 239+1 = 240 = 6th semiprime * 2^4 = 3 * 5 * 16.
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Jonathan Vos Post, Jul 13 2011
STATUS
approved