A228916 Indices of primes in sequence A108300.

1, 3, 9, 15, 39, 225, 231, 363, 687, 1299, 1335, 1809, 2367, 12735

Offset

1,2

Comments

Conjecture: for n>1 a(n) is a multiple of 3.

The indices greater than 363 yield probable primes. - Vaclav Kotesovec, Oct 28 2013

Next term > 100000. - Tyler Busby, Mar 29 2024

Links

Table of n, a(n) for n=1..14.

Mathematica

seq=RecurrenceTable[{a[n]==3*a[n-1]+a[n-2], a[0]==1, a[1]==5}, a, {n, 1, 1000}]; Select[Range[1000], PrimeQ[seq[[#]]]&]

Crossrefs

Cf. A108300, A209493, A001605, A001606, A096650, A099088.

Sequence in context: A350536 A133997 A057909 * A345431 A082702 A214771

Adjacent sequences: A228913 A228914 A228915 * A228917 A228918 A228919

Keyword

nonn,hard,more

Author

Vaclav Kotesovec, Sep 08 2013

Status

approved