A324534 The smallest common prime factor of sigma(n) and A276086(n), or 1 if no such prime exists.

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

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