Voozh

A227957

Number of primes that are of the form n - 2^k - k^2.

0, 0, 1, 1, 1, 2, 0, 2, 0, 2, 1, 1, 1, 2, 1, 1, 0, 1, 2, 3, 1, 2, 0, 2, 1, 1, 1, 1, 0, 2, 1, 2, 0, 3, 1, 1, 2, 1, 2, 2, 0, 1, 1, 2, 2, 2, 0, 2, 2, 1, 2, 0, 0, 2, 2, 1, 0, 1, 1, 3, 2, 3, 1, 3, 0, 0, 1, 2, 2, 3, 0, 1, 1, 3, 2, 3, 0, 1, 2, 2, 1, 1, 0, 2, 1, 2, 1, 2, 0, 2

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OFFSET

1,6

COMMENTS

Indices of zeros in the sequence are 1, 2, 7, 9, 17, 23, 29, 33, 41, 47, 52, ...

LINKS

Table of n, a(n) for n=1..90.

PROG

(PARI) a(n)=sum(k=0, log(n)\log(2), isprime(n-2^k-k^2)) \\ Charles R Greathouse IV, Mar 18 2014

CROSSREFS

Sequence in context: A052511 A054533 A339927 * A305575 A247977 A359239

Adjacent sequences: A227954 A227955 A227956 * A227958 A227959 A227960