A346471 a(n) = A344695(A276086(n)), where A344695(x) = gcd(psi(x), sigma(x)), and A276086 gives the prime product form of primorial base expansion of n.

1, 3, 4, 12, 1, 3, 6, 18, 24, 72, 6, 18, 1, 3, 4, 12, 1, 3, 6, 18, 24, 72, 12, 36, 1, 3, 4, 12, 1, 3, 8, 24, 32, 96, 8, 24, 48, 144, 192, 576, 48, 144, 8, 24, 32, 96, 8, 24, 48, 144, 192, 576, 96, 288, 8, 24, 32, 96, 8, 24, 1, 3, 4, 12, 3, 9, 6, 18, 24, 72, 18, 54, 3, 9, 12, 36, 3, 9, 12, 36, 48, 144, 36, 108, 3, 9, 12, 36

Offset

0,2

Links

Antti Karttunen, Table of n, a(n) for n = 0..11550

Index entries for sequences related to primorial base

Index entries for sequences related to sigma(n)

Formula

a(n) = A344695(A276086(n)) = gcd(A324653(n), A346470(n)).

Prog

(PARI)
A001615(n) = if(1==n, n, my(f=factor(n)); prod(i=1, #f~, f[i, 1]^f[i, 2] + f[i, 1]^(f[i, 2]-1))); \\ After code in A001615
A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
A344695(n) = gcd(sigma(n), A001615(n));
A346471(n) = A344695(A276086(n));

Crossrefs

Cf. A000203, A001615, A276086, A324653, A344695, A346470.

Cf. also A346469.

Sequence in context: A001112 A042079 A045826 * A084200 A348997 A354781

Adjacent sequences: A346468 A346469 A346470 * A346472 A346473 A346474

Keyword

nonn,base,look

Author

Antti Karttunen, Jul 21 2021

Status

approved