A246269 - OEIS

A246269

a(1) = 1, a(p(k)) = p(k+1) mod 4 for k-th prime p(k) and a(u * v) = a(u) * a(v) for u, v > 0.

1, 3, 1, 9, 3, 3, 3, 27, 1, 9, 1, 9, 1, 9, 3, 81, 3, 3, 3, 27, 3, 3, 1, 27, 9, 3, 1, 27, 3, 9, 1, 243, 1, 9, 9, 9, 1, 9, 1, 81, 3, 9, 3, 9, 3, 3, 1, 81, 9, 27, 3, 9, 3, 3, 3, 81, 3, 9, 1, 27, 3, 3, 3, 729, 3, 3, 3, 27, 1, 27, 1, 27, 3, 3, 9, 27, 3, 3, 3, 243, 1, 9, 1, 27, 9, 9, 3, 27

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OFFSET

1,2

COMMENTS

This is a fully multiplicative sequence. Only powers of 3 (A000244) occur as terms.

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..10080

FORMULA

a(n) = A065338(A003961(n)).

a(n) = A000244(A246270(n)).

EXAMPLE

For n = 10 = 2*5 = p_1 * p_3 we have a(n) = (p_{1+1} mod 4)*(p_{3+1} mod 4) = (p_2 mod 4) * (p_4 mod 4) = (3 mod 4)*(7 mod 4) = 3*3 = 9.