A130971 Smallest prime p, such that either |A000040(n)-p| or A000040(n)+p is of the form 2^k.

2, 2, 3, 3, 3, 3, 13, 3, 7, 3, 23, 5, 23, 11, 17, 11, 5, 3, 3, 7, 41, 47, 19, 73, 31, 37, 71, 43, 19, 97, 131, 3, 73, 11, 107, 23, 29, 131, 89, 83, 163, 53, 127, 191, 59, 71, 83, 191, 29, 101, 23, 17, 113, 5, 193, 7, 13, 239, 149, 277, 229, 37, 179, 307, 199, 61, 181, 353, 283

Offset: 1

Author

Antti Karttunen, Jun 19 2007

Keywords

• nonn

Links

• Ray Chandler, Table of n, a(n) for n=1..10000

Crossrefs

Cf. A130971, A130972, A103150.

Programs

Scheme

(define (A130971 n) (let ((p1 (A000040 n))) (let loop ((i 1) (p2 2)) (cond ((pow2? (abs (- p1 p2))) p2) ((pow2? (+ p1 p2)) p2) (else (loop (+ i 1) (A000040 (+ i 1))))))))
(define (pow2? n) (and (> n 0) (zero? (A004198bi n (- n 1)))))

Extensions

Extended by Ray Chandler, Aug 06 2010