A113843 Tetranacci analog of A055502.

0, 2, 3, 7, 13, 29, 53, 103, 199, 389, 751, 1447, 2789, 5381, 10369, 19991, 38543, 74287, 143197, 276019, 532061, 1025579, 1976857, 3810517, 7345031, 14158009, 27290429, 52604017, 101397487, 195449957, 376741891, 726193373, 1399782719, 2698167947, 5200885961

Offset

0,2

Comments

This is to the tribonacci sequence as A055502 is to the Fibonacci sequence and A113823 is to the tribonacci sequence (i.e., least prime greater than the sum of the previous 2 terms in A055502, least prime greater than the sum of the previous 3 terms in A113823, least prime greater than the sum of the previous 4 terms in this sequence).

Links

Harvey P. Dale, Table of n, a(n) for n = 0..1000

Formula

a(-n) = a(0) = 0, a(1) = 2, for n>1: a(n) = smallest prime > a(n-1)+a(n-2)+a(n-3)+a(n-4).

Example

a(15) = 19991 because a(11)+a(12)+a(13)+a(14) = 1447 + 2789 + 5381 + 10369 = 19986 and 19991 is the smallest prime > 19986.

Mathematica

nxt[{a_, b_, c_, d_}]:={b, c, d, NextPrime[a+b+c+d]}; Transpose[ NestList[ nxt, {0, 2, 3, 7}, 40]][[1]] (* Harvey P. Dale, Sep 18 2013 *)

Crossrefs

Cf. A055502, A113823.

Sequence in context: A233557 A296415 A113823 * A199582 A255516 A113884

Adjacent sequences: A113840 A113841 A113842 * A113844 A113845 A113846

Keyword

easy,nonn

Author

Jonathan Vos Post, Jan 24 2006

Extensions

More terms from Harvey P. Dale, Sep 18 2013

Status

approved