A036971 Numbers k such that the k-th Fibonacci number reversed is prime.

3, 4, 5, 7, 9, 14, 17, 21, 25, 26, 65, 98, 175, 191, 382, 497, 653, 1577, 1942, 1958, 2405, 4246, 4878, 5367, 9142, 9318, 10921, 17833, 20433, 50373, 66571, 85098, 93699, 104075

Offset: 1

Author

G. L. Honaker, Jr., Carlos Rivera

Keywords

• nonn
• base
• more

Comments

Numbers k such that the k-th Fibonacci number appears in A095179. - Iain Fox, Oct 28 2017

Crossrefs

Cf. A036797, A036972, A095179.

Programs

Maple

revdigs:= proc(n) local L;
L:= convert(n,base,10);
add(L[-i]*10^(i-1),i=1..nops(L))
end proc:
select(isprime@revdigs@combinat:-fibonacci, [$1..10000]); # Robert Israel, Oct 29 2017

Mathematica

a = Table[FromDigits[Reverse[IntegerDigits[Fibonacci[j]]]], {j, 10000}]; b = Select[a, PrimeQ[ # ] &]; Flatten[Table[Position[a, b[[i]]], {i, 1, Length[b]}]]
Select[Range[9400],PrimeQ[IntegerReverse[Fibonacci[#]]]&] (* The program uses the IntegerReverse function from Mathematica version 10 *) (* Harvey P. Dale, Dec 08 2015 *)

PARI

lista(nn) = for(n=3, nn, if(ispseudoprime(eval(concat(Vecrev(Str(fibonacci(n)))))), print1(n, ", "))) \\ Iain Fox, Oct 28 2017

Extensions

a(25)-a(26) from Vit Planocka (planocka(AT)mistral.cz), Feb 25 2003

Offset corrected by Arkadiusz Wesolowski, Jan 12 2012

a(27)-a(31) from Iain Fox, Oct 28 2017

a(32)-a(33) from Iain Fox, Oct 29 2017

a(34) from Iain Fox, Aug 24 2021