A340683 a(n) = A007949((A003961(A003961(n))+1)/2), where A003961 shifts the prime factorization of n one step towards larger primes, and A007949(x) gives the exponent of largest power of 3 dividing x.

0, 1, 0, 0, 1, 2, 0, 2, 0, 0, 2, 0, 0, 1, 1, 0, 1, 1, 1, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 1, 1, 0, 2, 0, 0, 0, 0, 0, 1, 1, 3, 1, 3, 1, 1, 0, 0, 1, 4, 0, 0, 1, 0, 1, 1, 1, 0, 2, 2, 0, 0, 0, 1, 0, 0, 2, 0, 0, 0, 1, 1, 3, 0, 1, 1, 2, 2, 2, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 2, 0, 0, 1, 0, 2, 1, 0, 3, 0, 0, 3, 1

Offset: 1

Author

Antti Karttunen, Feb 14 2021

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..65537
• Index entries for sequences computed from indices in prime factorization

Crossrefs

Cf. A003961, A007949, A048673, A292251, A341347.

Programs

PARI

A003961(n) = { my(f=factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); }; \\ From A003961
A340683(n) = valuation((A003961(A003961(n))+1)/2, 3);

Formula

a(n) = A292251(A003961(n)) = A007949(A048673(A003961(n))).