A092836 Prime tribonacci numbers.

2, 7, 13, 149, 19341322569415713958901, 15762679542071167858843489, 145082467753351661438130501937754420584096000083183992629

Offset: 1

Author

Eric W. Weisstein, Mar 06 2004

Keywords

• nonn

Comments

The next term has 212 digits and is too large to fit. - Harvey P. Dale, Oct 08 2017

These primes are A000073(k) at k = 4, 6, 7, 11, 87, 98, 215, 802, 4202, ... The indices in A092835 are off by one. - R. J. Mathar, Dec 14 2011

Links

• Harry J. Smith, Table of n, a(n) for n = 1..8
• 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
• Eric Weisstein's World of Mathematics, Tribonacci Number

Crossrefs

Cf. A000073, A092835, A056816.

Programs

Mathematica

Select[LinearRecurrence[{1,1,1},{0,0,1},1000],PrimeQ] (* Harvey P. Dale, Oct 08 2017 *)

PARI

t(m)= { if (m==0, return(a1)); if (m==1, return(a2)); if (m==2, return(a3)); r = a1 + a2 + a3; a1=a2; a2=a3; a3=r; return(r); } { a1=0; a2=1; a3=1; n=0; for (m=0, 1000, a=t(m); if (isprime(a), write("b092836.txt", n++, " ", a))); } \\ Harry J. Smith, Jun 21 2009