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A324534 The smallest common prime factor of sigma(n) and A276086(n), or 1 if no such prime exists. 2
1, 3, 2, 1, 2, 1, 2, 3, 1, 3, 2, 1, 2, 3, 2, 1, 2, 1, 2, 3, 2, 3, 2, 5, 1, 3, 2, 1, 2, 1, 2, 3, 2, 3, 2, 7, 2, 3, 2, 3, 2, 1, 2, 3, 2, 3, 2, 1, 1, 3, 2, 7, 2, 5, 2, 3, 2, 3, 2, 7, 2, 3, 2, 1, 2, 1, 2, 3, 2, 3, 2, 5, 2, 3, 2, 5, 2, 7, 2, 3, 1, 3, 2, 7, 2, 3, 2, 3, 2, 1, 2, 3, 2, 3, 2, 7, 2, 3, 2, 7, 2, 1, 2, 3, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..30030

Index entries for sequences related to primorial base

Index entries for sequences related to primorial numbers

Index entries for sequences related to sigma(n)

FORMULA

a(n) = A020639(A324644(n)) = A020639(gcd(A000203(n),A276086(n))).

PROG

(PARI)

A276086(n) = { my(i=0, m=1, pr=1, nextpr); while((n>0), i=i+1; nextpr = prime(i)*pr; if((n%nextpr), m*=(prime(i)^((n%nextpr)/pr)); n-=(n%nextpr)); pr=nextpr); m; };

A020639(n) = if(1==n, n, factor(n)[1, 1]);

A324534(n) = A020639(gcd(sigma(n), A276086(n)));

CROSSREFS

Cf. A000203, A020639, A276086, A324644.

Sequence in context: A175191 A328928 A342468 * A248505 A254629 A096248

Adjacent sequences:  A324531 A324532 A324533 * A324535 A324536 A324537

KEYWORD

nonn

AUTHOR

Antti Karttunen, Mar 11 2019

STATUS

approved

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Last modified September 21 07:28 EDT 2021. Contains 347596 sequences. (Running on oeis4.)