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A120635 Replace each prime power in the prime-factorization of n with the next higher prime-power. 2
1, 3, 4, 5, 7, 12, 8, 9, 11, 21, 13, 20, 16, 24, 28, 17, 19, 33, 23, 35, 32, 39, 25, 36, 27, 48, 29, 40, 31, 84, 32, 37, 52, 57, 56, 55, 41, 69, 64, 63, 43, 96, 47, 65, 77, 75, 49, 68, 53, 81, 76, 80, 59, 87, 91, 72, 92, 93, 61, 140, 64, 96, 88, 67, 112, 156, 71, 95, 100, 168, 73 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..71.

EXAMPLE

12 = 2^2 *3^1. 5 is the prime power closest to 2^2 and larger than 2^2. 4 is the prime power closest to 3 and larger than 3. So a(12) = 5*4 = 20.

PROG

(PARI) { a(n) = local(f, r, k, d); f=factorint(n); r=1; for(i=1, matsize(f)[1], k=f[i, 1]^f[i, 2]+1; while(!isprime(k) && (!ispower(k, , &d)||!isprime(d)), k++); r*=k); r } - Max Alekseyev, Feb 01 2007

CROSSREFS

Cf. A120636.

Sequence in context: A046413 A285224 A322991 * A300841 A023713 A032890

Adjacent sequences:  A120632 A120633 A120634 * A120636 A120637 A120638

KEYWORD

nonn,mult

AUTHOR

Leroy Quet, Jun 22 2006

EXTENSIONS

More terms from Max Alekseyev, Feb 01 2007

STATUS

approved

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Last modified June 18 17:05 EDT 2019. Contains 324214 sequences. (Running on oeis4.)