A178095 - OEIS

A178095

a(1)=a(2)=a(3)=1; thereafter a(n) = lpf(a(n-1)+a(n-2)+a(n-3)), where lpf = "least prime factor".

1, 1, 1, 3, 5, 3, 11, 19, 3, 3, 5, 11, 19, 5, 5, 29, 3, 37, 3, 43, 83, 3, 3, 89, 5, 97, 191, 293, 7, 491, 7, 5, 503, 5, 3, 7, 3, 13, 23, 3, 3, 29, 5, 37, 71, 113, 13, 197, 17, 227, 3, 13, 3, 19, 5, 3, 3, 11, 17, 31, 59, 107, 197, 3, 307, 3, 313, 7, 17, 337, 19, 373, 3, 5, 3, 11, 19, 3, 3, 5, 11, 19, 5, 5, 29, 3, 37, 3, 43, 83, 3, 3, 89, 5, 97, 191, 293, 7, 491, 7

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OFFSET

1,4

COMMENTS

Has period 69, starting with the fourth term: 3, 5, 3, 11, 19, 3, 3, 5, 11, ...

LINKS

Table of n, a(n) for n=1..100.

MATHEMATICA

nxt[{a_, b_, c_}]:={b, c, FactorInteger[a+b+c][[1, 1]]}; Transpose[ NestList[ nxt, {1, 1, 1}, 100]][[1]] (* Harvey P. Dale, Aug 19 2014 *)

CROSSREFS

Cf. A178094, A020639, A175723, A177904.

Sequence in context: A105445 A345014 A328878 * A177904 A049072 A059887

Adjacent sequences: A178092 A178093 A178094 * A178096 A178097 A178098

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Dec 16 2010

STATUS

approved