A120430 - OEIS

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A120430

Greater of prime powers that differ by 1. In other words, numbers n such that n-1 and n are prime powers.

27

2, 3, 4, 5, 8, 9, 17, 32, 128, 257, 8192, 65537, 131072, 524288, 2147483648, 2305843009213693952, 618970019642690137449562112, 162259276829213363391578010288128

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OFFSET

1,1

COMMENTS

See comments in A006549.

LINKS

Table of n, a(n) for n=1..18.

FORMULA

a(n) = A006549(n) + 1. - Michel Marcus, Aug 25 2013

PROG

(PARI) isokp(n) = (n==1) || isprime(n) || (ispower(n, , &k) && isprime(k));

isok(n) = isokp(n) && isokp(n-1); \\ Michel Marcus, Aug 25 2013

CROSSREFS

Sequence in context: A330400 A306044 A263581 * A295033 A152606 A057911

Adjacent sequences: A120427 A120428 A120429 * A120431 A120432 A120433

KEYWORD

nonn

AUTHOR

Greg Huber, Jul 13 2006

STATUS

approved