A178838 Indices n such that the sums of the squares of the digits of Fibonacci(n) are prime.

8, 14, 15, 18, 22, 25, 27, 29, 39, 44, 45, 46, 47, 65, 68, 69, 90, 94, 100, 103, 104, 107, 113, 116, 124, 133, 135, 138, 157, 164, 165, 166, 167, 168, 172, 175, 177, 187, 188, 193, 207, 223, 226, 229, 233, 247, 257, 260, 263, 265, 266, 270, 273, 276, 295, 299

Offset

1,1

Links

Table of n, a(n) for n=1..56.

Example

8 is in the sequence because Fibonacci(8)=21, and 2^2 + 1^2 = 5 prime ;
14 is in the sequence because Fibonacci(14)=377,and 3^2 + 7^2 + 7^2 = 107 prime.

Maple

with(combinat, fibonacci):nn:= 120: for n from 1 to 700 do:p:=fibonacci(n):l:=length(p):n0:=p:s:=0:for m from 1 to l do:q:=n0:u:=irem(q, 10):v:=iquo(q, 10):n0:=v :s:=s+u^2:od:if type(s, prime)=true then printf(`%d, `, n): else fi:od:

Mathematica

Flatten[Position[Fibonacci[Range[300]], _?(PrimeQ[Total[ IntegerDigits[ #]^2]]&), {1}, Heads->False]] (* Harvey P. Dale, Aug 31 2014 *)

Crossrefs

Cf. A000045

Sequence in context: A092537 A226799 A236295 * A219303 A376519 A082772

Adjacent sequences: A178835 A178836 A178837 * A178839 A178840 A178841

Keyword

nonn,base

Author

Michel Lagneau, Jun 17 2010

Status

approved