A342805 a(n) = (1/n)*(product of the terms of the n-th row of A177028).

1, 1, 1, 3, 1, 1, 4, 3, 1, 5, 1, 1, 18, 4, 1, 7, 1, 1, 24, 5, 1, 9, 4, 1, 10, 18, 1, 11, 1, 1, 12, 7, 5, 156, 1, 1, 14, 8, 1, 15, 1, 1, 288, 9, 1, 17, 4, 1, 90, 10, 1, 19, 21, 1, 20, 11, 1, 21, 1, 1, 22, 48, 8, 414, 1, 1, 24, 65, 1, 25, 1, 1, 234, 14, 1, 81, 1, 1, 784, 15

Offset: 3

Author

Michel Marcus, Mar 22 2021

Keywords

• nonn

Examples

			For n=3, A177028 row is (3), so a(3) = 3/3 = 1.
For n=6, A177028 row is (6, 3), so a(6) = 6*3/6 = 3.
For n=15, A177028 row is (15, 6, 3), so a(15) = 15*6*3/15 = 18.
		

Links

• Michel Marcus, Table of n, a(n) for n = 3..10000

Crossrefs

Cf. A090466, A090467, A177028, A342772.

Programs

PARI

row(n)=my(v=List()); fordiv(2*n, k, if(k<2, next); if(k==n, break); my(s=(2*n/k-4+2*k)/(k-1)); if(denominator(s)==1, listput(v, s))); Vec(v); \\ A177028
a(n) = vecprod(row(n))/n;

Formula

For m in A090466, a(m) > 1.

For m in A090467, a(m) = 1.