login
A062614
Squarefree parts of products of numbers of faces of Platonic solids.
1
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
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
KEYWORD
nonn
AUTHOR
Neil Fernandez, Jul 04 2001
EXTENSIONS
More terms from Michel Marcus, Feb 03 2015
STATUS
approved