OFFSET
2,2
COMMENTS
p = Prime[n] divides a(n) for p = {29,89,101,181,229,349,401,461,509,521,541,709,761,769,809,...} = A047650[n] Primes for which golden mean tau is a quadratic residue or Primes of the form x^2+20y^2.
FORMULA
a(n) = Fibonacci[ (Prime[n]+3)/2 ] - 1, n>1. a(n) = Sum[ Fibonacci[k], {k,1,(p-1)/2} ], p = Prime[n], n>1.
MATHEMATICA
Table[Fibonacci[(Prime[n]+3)/2]-1, {n, 2, 50}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Alexander Adamchuk, Aug 08 2006
STATUS
approved