A319990 a(n) = Product_{d|n, d<n} A019565(d)^[0 == d mod 3].

1, 1, 1, 1, 1, 6, 1, 1, 6, 1, 1, 90, 1, 1, 6, 1, 1, 1260, 1, 1, 6, 1, 1, 3150, 1, 1, 84, 1, 1, 18900, 1, 1, 6, 1, 1, 1455300, 1, 1, 6, 1, 1, 9900, 1, 1, 17640, 1, 1, 242550, 1, 1, 6, 1, 1, 19209960, 1, 1, 6, 1, 1, 764032500, 1, 1, 9240, 1, 1, 2340, 1, 1, 6, 1, 1, 7283776500, 1, 1, 1260, 1, 1, 35100, 1, 1, 38808, 1, 1, 94594500, 1, 1, 6, 1, 1

Offset

1,6

Links

Antti Karttunen, Table of n, a(n) for n = 1..8192

Formula

a(n) = Product_{d|n, d<n} A019565(d)^[0 == d mod 3].

a(n) = A293214(n) / (A319991(n)*A319992(n)).

For all n >= 1:

A007814(a(n)) = A320003(n).

A195017(a(n)) = 0 mod 3.

Prog

(PARI)
A019565(n) = {my(j, v); factorback(Mat(vector(if(n, #n=vecextract(binary(n), "-1..1")), j, [prime(j), n[j]])~))}; \\ From A019565
A319990(n) = { my(m=1); fordiv(n, d, if((d<n)&&(0==(d%3)), m *= A019565(d))); m; };

Crossrefs

Cf. A293214, A319991, A319992, A320003, A320010 (rgs-transform).

Sequence in context: A182429 A325385 A195385 * A138073 A131778 A095713

Adjacent sequences: A319987 A319988 A319989 * A319991 A319992 A319993

Keyword

nonn

Author

Antti Karttunen, Oct 03 2018

Status

approved