A104577 Indices of prime generalized tetranacci numbers, A073817.

2, 3, 8, 9, 16, 19, 24, 27, 46, 68, 71, 78, 107, 198, 309, 377, 477, 1057, 1631, 2419, 3974, 4293, 8247, 10513, 10709, 12011, 15042, 30543, 31607, 39664, 47552, 145858

Offset

1,1

Comments

The sequence of generalized tetranacci numbers is defined as beginning with 1, 3, 7, 15. Subsequent terms are the sum of the previous four terms. Note that the sequence of these generalized tetranacci numbers has many more primes than the tetranacci sequence A000078 (whose prime indices are in A104534).

Links

Table of n, a(n) for n=1..32.

Tony D. Noe and Jonathan Vos Post, Primes in Fibonacci n-step and Lucas n-step Sequences, J. of Integer Sequences, Vol. 8 (2005), Article 05.4.4

Mathematica

a={-1, -1, -1, 4}; Do[s=Plus@@a; a=RotateLeft[a]; a[[4]]=s; If[PrimeQ[s], Print[n]], {n, 30000}]

Crossrefs

Cf. A104576 (indices of prime generalized tribonacci numbers).

Sequence in context: A331821 A093765 A260020 * A372824 A309017 A376191

Adjacent sequences: A104574 A104575 A104576 * A104578 A104579 A104580

Keyword

nonn

Author

T. D. Noe, Mar 16 2005

Status

approved