A102137 Iccanobirt prime indices (7 of 15): Indices of prime numbers in A102117.

4, 6, 7, 19, 43, 48, 109, 122, 628, 1689, 6208, 6309, 15479, 21651

Offset: 1

Author

Jonathan Vos Post and Ray Chandler, Dec 31 2004

Keywords

• nonn
• more
• base

Comments

a(15) > 50000. - Robert Price, Nov 09 2018

Crossrefs

Cf. A000040, A102117, A102131-A102145.

Programs

Maple

rev:= proc(n) local i, L;
L:= convert(n,base, 10);
add(L[-i]*10^(i-1),i=1..nops(L))
end proc:
A[0]:= 0: A[1]:= 0: A[2]:= 1:
RA[0]:=0: RA[1]:= 0: RA[2]:= 1:
count:= 0:
for n from 3 to 10000 do
  A[n]:= RA[n-1]+RA[n-2]+RA[n-3];
  RA[n]:= rev(A[n]);
  if isprime(A[n]) then count:= count+1; a[count]:= n fi
od:
seq(a[i],i=1..count); # Robert Israel, Aug 04 2016

Mathematica

Flatten[Position[Transpose[NestList[nxt,{0,0,1},1700]][[1]],?PrimeQ]]-1 (* _Harvey P. Dale, Nov 28 2015 *)

Formula

A102117(a(n)) = A102157(n).

Extensions

a(11)-a(13) from Robert Israel, Aug 04 2016

a(14) from Robert Price, Nov 09 2018