A328829 Index of the least significant digit > 1 in the primorial base expansion of A276086(n), 0 if no such digit exists.

0, 0, 0, 0, 0, 3, 2, 2, 3, 0, 3, 4, 3, 3, 3, 4, 3, 5, 2, 2, 3, 4, 3, 4, 3, 3, 3, 4, 3, 4, 0, 3, 3, 3, 4, 4, 2, 2, 3, 0, 3, 5, 3, 3, 3, 5, 3, 5, 2, 2, 3, 5, 3, 5, 3, 3, 3, 5, 3, 6, 3, 4, 3, 3, 3, 3, 2, 2, 3, 5, 3, 5, 3, 3, 3, 5, 3, 5, 2, 2, 3, 5, 3, 5, 3, 3, 3, 5, 3, 5, 3, 3, 4, 3, 3, 3, 2, 2, 3, 5, 3, 5, 3, 3, 3, 5

Offset: 0

Author

Antti Karttunen, Oct 29 2019

Keywords

• nonn

Comments

a(n) = index of the least non-unitary prime divisor of A276087(n) or 0 if no such prime-divisor exists.

Links

• Antti Karttunen, Table of n, a(n) for n = 0..65537
• Index entries for sequences related to primorial base

Crossrefs

Cf. A276086, A276087, A277885, A328828, A328836 (positions of zeros).

Programs

PARI

A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
A328828(n) = { my(i=1, p=2); while(n, if((n%p)>1, return(i)); i++; n = n\p; p = nextprime(1+p)); (0); };
A328829(n) = A328828(A276086(n));

PARI

A277885(n) = if(1==n,0,my(f=factor(n)); for(i=1,#f~,if(f[i,2]>1,return(primepi(f[i,1])))); (0));
A328829(n) = A277885(A276086(A276086(n)));

Formula

a(n) = A328828(A276086(n)) = A277885(A276087(n)).