A062614 Squarefree parts of products of numbers of faces of Platonic solids.

1, 6, 2, 3, 1, 5, 6, 2, 1, 3, 1, 2, 5, 6, 30, 2, 1, 10, 3, 6, 15, 1, 2, 5, 6, 1, 3, 30, 2, 1, 10, 5, 3, 6, 15, 1, 2, 5, 1, 10, 6, 1, 3, 30, 2, 1, 6, 10, 2, 5, 3, 2, 6, 15, 1, 30, 2, 3, 5, 1, 10, 6, 1, 3, 30, 6, 5, 2, 15, 1, 6, 10, 2, 5, 3, 2, 6, 1, 15, 3, 1

Offset

1,2

Links

Table of n, a(n) for n=1..81.

Formula

a(n) = A007913(A062554(n)). - Michel Marcus, Feb 03 2015

Example

32 is the eighth smallest number expressible as a product of members of {4,6,8,12,20}, namely as 4x8. The largest square divisor of 32 is 16. 32/16=2, so a(8)=2.

Prog

(PARI) ismult(n, v, vp) = {for (k=1, #v, q = n/v[k]; if ((type(q)== "t_INT") && vecsearch(vp, q), return (1)); ); }
lista(nn) = {v = [4, 6, 8, 12, 20]; vp = []; for (n=2, nn, if (vecsearch(v, n) || ismult(n, v, vp), print1(core(n), ", "); vp = concat(vp, n); ); ); } \\ Michel Marcus, Feb 03 2015

Crossrefs

Cf. A062554.

Sequence in context: A272354 A353121 A196552 * A155527 A196525 A300892

Adjacent sequences: A062611 A062612 A062613 * A062615 A062616 A062617

Keyword

nonn

Author

Neil Fernandez, Jul 04 2001

Extensions

More terms from Michel Marcus, Feb 03 2015

Status

approved