A303264 Indices of primes in tetranacci sequence A000078.

5, 9, 13, 14, 38, 58, 403, 2709, 8419, 14098, 31563, 50698, 53194, 155184

Offset

1,1

Comments

T = A000078 is defined by T(n) = Sum_{k=1..4} T(n-k), T(3) = 1, T(n) = 0 for n < 3.

The largest terms correspond to unproven probable primes T(a(n)).

Links

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

Formula

a(n) = A104534(n) + 2.

Prog

(PARI) a(n, N=5, S=vector(N, i, i>N-2))={for(i=N, oo, ispseudoprime(S[i%N+1]=2*S[(i-1)%N+1]-S[i%N+1])&&!n--&&return(i))}

Crossrefs

Cf. A000045, A000073, A000078, A001591, A001592, A122189 (or A066178), ... (Fibonacci, tribonacci, tetranacci numbers).

Cf. A005478, A092836, A104535, A105757, A105759, A105761, ... (primes in Fibonacci numbers and above generalizations).

Cf. A001605, A303263, A303264, A248757, A249635, ... (indices of primes in A000045, A000073, A000078, ...).

Cf. A247027: Indices of primes in the tetranacci sequence A001631 (starting 0, 0, 1, 0...), A104534 (a variant: a(n) - 2), A105756 (= A248757 - 3), A105758 (= A249635 - 4).

Sequence in context: A304868 A080579 A325274 * A165971 A160522 A314651

Adjacent sequences: A303261 A303262 A303263 * A303265 A303266 A303267

Keyword

nonn,hard,more

Author

M. F. Hasler, Apr 18 2018

Status

approved