A209493 Indices of primes in sequence A006190.

2, 5, 11, 17, 61, 103, 167, 193, 293, 643, 647, 911, 11243, 29437, 55021, 80141

Offset: 1

Author

Vaclav Kotesovec, Mar 09 2012

Keywords

• nonn
• hard
• more

Comments

Index must be prime. The indices greater than 293 yield probable primes.

Crossrefs

Cf. A006190, A006497, A000129, A096650.

Programs

Mathematica

seq=RecurrenceTable[{a[n]==3*a[n-1]+a[n-2], a[1]==1, a[2]==3}, a, {n, 1000}]; Select[Range[1000], PrimeQ[seq[[#]]]&]

Extensions

a(14)-a(15) from Vaclav Kotesovec, Sep 08 2013

a(16) from Michael S. Branicky, Nov 03 2024