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A228916
Indices of primes in sequence A108300.
1
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
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
KEYWORD
nonn,hard,more
AUTHOR
Vaclav Kotesovec, Sep 08 2013
STATUS
approved