A102140 Iccanobirt prime indices (10 of 15): Indices of prime numbers in A102120.

4, 6, 7, 11, 12, 20, 25, 45, 113, 193, 1214, 1272, 2435, 4007, 12258, 12771, 14166, 27368, 29184

Offset: 1

Author

Jonathan Vos Post and Ray Chandler, Dec 31 2004

Keywords

• nonn
• more
• base

Comments

No more terms through 5000.

a(20) > 50000. - Robert Price, Nov 10 2018

Crossrefs

Cf. A000040, A102120, A102131-A102145.

Programs

Mathematica

b[0] = b[1] = 0; b[2] = 1; b[n_] := b[n] = IntegerReverse[b[n - 1] + IntegerReverse[b[n - 2]] + b[n - 3]];
Reap[Do[If[PrimeQ[b[n]], Print[n]; Sow[n]], {n, 5000}]][[2, 1]] (* Jean-François Alcover, Dec 15 2017 *)

Formula

A102120(a(n)) = A102160(n).

Extensions

a(15)-a(19) from Robert Price, Nov 10 2018