A193294 Sum of even divisors of Fibonacci(n).

0, 0, 2, 0, 0, 14, 0, 0, 36, 0, 0, 390, 0, 0, 744, 0, 0, 5040, 0, 0, 11816, 0, 0, 154752, 0, 0, 213840, 0, 0, 1999872, 0, 0, 3564360, 0, 0, 46656000, 0, 0, 63517896, 0, 0, 526048320, 0, 0, 1465647264, 0, 0, 16665772032, 0, 0, 20377766312, 0, 0, 173039328000

Offset: 1

Author

Michel Lagneau, Jul 21 2011

Keywords

• nonn

Examples

			a(6) = 14 because Fibonacci(6) = 8, and the sum of the even divisors {2, 4, 8} = 14.
		

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A000045, A193291.

Programs

Mathematica

Table[Total[Select[Divisors[Fibonacci[n]], EvenQ[ # ]&]], {n, 75}]

PARI

a(n)=if(n%3,0,2*sigma(fibonacci(n)/2)) \\ Charles R Greathouse IV, Jul 31 2011