A085767 Smallest m such that n divides the pentagonal number A000326(m).

1, 3, 3, 3, 2, 3, 5, 11, 9, 7, 4, 3, 9, 7, 12, 11, 6, 27, 13, 27, 12, 4, 8, 27, 17, 35, 27, 19, 10, 12, 21, 43, 15, 23, 5, 27, 25, 19, 9, 27, 14, 12, 29, 11, 27, 8, 16, 75, 33, 67, 6, 35, 18, 27, 15, 75, 51, 39, 20, 27, 41, 31, 54, 43, 22, 15, 45, 40, 54, 7, 24, 27, 49, 99, 42, 19, 26, 39

Offset

1,2

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

Let pe(m)=m*(3m-1)/2. The pe(1)=1, pe(2)=5, pe(3)=12. As pe(3) is the first divisible by 6, a(6)=3.

Mathematica

smn[n_]:=Module[{m=1, c}, c=(m(3m-1))/2; While[!Divisible[c, n], m++; c=(m(3m-1))/2]; m]; Array[smn, 80] (* Harvey P. Dale, Feb 03 2015 *)

Prog

(PARI) pe(n)=n*(3*n-1)/2 for (n=1, 50, c=1; while (pe(c)%n!=0, c++); print1(c", "))

Crossrefs

Cf. A011772 (triangular numbers), A019554 (squares).

Sequence in context: A306996 A166007 A087497 * A082127 A031354 A307486

Adjacent sequences: A085764 A085765 A085766 * A085768 A085769 A085770

Keyword

nonn

Author

Jon Perry, Jul 22 2003

Extensions

More terms from David Wasserman, Feb 10 2005

Status

approved