cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A319992 a(n) = Product_{d|n, dA019565(d)^[2 == d mod 3].

Original entry on oeis.org

1, 1, 1, 3, 1, 3, 1, 3, 1, 30, 1, 3, 1, 3, 10, 21, 1, 3, 1, 30, 1, 126, 1, 21, 10, 3, 1, 315, 1, 30, 1, 21, 42, 66, 10, 3, 1, 3, 1, 11550, 1, 315, 1, 126, 10, 990, 1, 21, 1, 30, 22, 693, 1, 3, 420, 2205, 1, 2310, 1, 1650, 1, 3, 1, 273, 10, 126, 1, 66, 330, 245700, 1, 21, 1, 3, 10, 585, 42, 693, 1, 11550, 1, 546, 1, 315, 220, 3, 770
Offset: 1

Views

Author

Antti Karttunen, Oct 03 2018

Keywords

Crossrefs

Cf. also A293222.

Programs

  • PARI
    A019565(n) = {my(j,v); factorback(Mat(vector(if(n, #n=vecextract(binary(n), "-1..1")), j, [prime(j), n[j]])~))}; \\ From A019565
    A319992(n) = { my(m=1); fordiv(n,d,if((dA019565(d))); m; };

Formula

a(n) = Product_{d|n, dA019565(d)^[2 == d mod 3].
a(n) = A293214(n) / (A319990(n)*A319991(n)).
For all n >= 1:
A007814(a(n)) = A320005(n).
A048675(a(n)) = A293898(n).
A195017(a(n)) = -A293896(n) mod 3.