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A252374 a(n) = exponent k for the smallest r such that r^k <= spf(n) and gpf(n) < r^(k+1), for some k >= 0, where spf and gpf (smallest and greatest prime factor of n) are given by A020639(n) and A006530(n). 3
0, 1, 1, 1, 2, 1, 2, 1, 1, 0, 3, 1, 3, 0, 1, 1, 4, 1, 4, 0, 1, 0, 4, 1, 2, 0, 1, 0, 4, 0, 4, 1, 0, 0, 2, 1, 5, 0, 0, 0, 5, 0, 5, 0, 1, 0, 5, 1, 2, 0, 0, 0, 5, 1, 1, 0, 0, 0, 5, 0, 5, 0, 1, 1, 1, 0, 6, 0, 0, 0, 6, 1, 6, 0, 1, 0, 1, 0, 6, 0, 1, 0, 6, 0, 1, 0, 0, 0, 6, 0, 1, 0, 0, 0, 1, 1, 6, 0, 0, 0, 6, 0, 6, 0, 1, 0, 6, 1, 6, 0, 0, 0, 6, 0, 1, 0, 0, 0, 1, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..10000

FORMULA

Other identities. For all n >= 1:

a(n) = a(A066048(n)). [The result depends only on the smallest and the largest prime factor of n.]

PROG

(Scheme) (define (A252374 n) (let ((spf (A020639 n)) (gpf (A006530 n))) (let outerloop ((r 2)) (let innerloop ((rx 1) (k 0)) (cond ((and (<= rx spf) (< gpf (* r rx))) k) ((<= rx spf) (innerloop (* r rx) (+ 1 k))) (else (outerloop (+ 1 r))))))))

CROSSREFS

Cf. A252375.

Cf. A251727 (gives the position of other zeros after a(1)=0).

Cf. also A006530, A020639, A066048.

Sequence in context: A029443 A078508 A029416 * A161780 A136571 A178562

Adjacent sequences:  A252371 A252372 A252373 * A252375 A252376 A252377

KEYWORD

nonn

AUTHOR

Antti Karttunen, Dec 17 2014

STATUS

approved

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Last modified July 9 04:34 EDT 2020. Contains 335538 sequences. (Running on oeis4.)