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proposed

The smallest common prime factor of sigma(n) and A276086(n), or 1 if no such prime exists; a(n) = A020639(gcd(sigma(n),A276086(n)))..

Antti Karttunen, <a href="/A324534/b324534.txt">Table of n, a(n) for n = 1..30030</a>

The smallest common prime factor of sigma(n) and A276086(n), 1 if no such prime exists; a(n) = A020639(gcd(sigma(n),A276086(n))).

allocated for Antti Karttunen

a(n) = A020639(gcd(sigma(n),A276086(n))).

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

1,2

<a href="/index/Pri#primorialbase">Index entries for sequences related to primorial base</a>

<a href="/index/Pri#primorial_numbers">Index entries for sequences related to primorial numbers</a>

<a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>

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

(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)));

Cf. A000203, A020639, A276086, A324644.

allocated

nonn

Antti Karttunen, Mar 11 2019

approved

editing

allocated for Antti Karttunen

allocated

approved