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

Author

Jonathan Vos Post, Jan 24 2006

Keywords

• easy
• nonn

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).

Examples

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

Links

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

Crossrefs

Cf. A055502, A113823.

Programs

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 *)

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).

Extensions

More terms from Harvey P. Dale, Sep 18 2013