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
Keywords
Examples
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.
Links
- Harvey P. Dale, Table of n, a(n) for n = 1..1000
Programs
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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 *) -
PARI
pe(n)=n*(3*n-1)/2 for (n=1,50,c=1; while (pe(c)%n!=0,c++); print1(c","))
Extensions
More terms from David Wasserman, Feb 10 2005