A142885 Primes that appear in the sequence: a(n) = 1 if a(n-1) is prime; otherwise a(n) = a(n-1)+a(n-2), with a(1) = 1.

2, 3, 5, 7, 17, 19, 41, 43, 89, 181, 16253, 341347, 682697, 682699, 23211821, 1468054608334661, 1029706322806826946897683, 1497696634290068254884323345209574043499520759403786997

Offset

1,1

Comments

Interesting that at the start the primes seem to come in pairs.

Links

Table of n, a(n) for n=1..18.

Mathematica

Clear[a, n]; a[0] = 0; a[1] = 1; a[n_] := a[n] = If[PrimeQ[a[n - 1]], 1, a[n - 1] + a[n - 2]]; Flatten[Table[If[PrimeQ[a[n]], a[n], {}], {n, 0, 400}]]

Crossrefs

Sequence in context: A158085 A119833 A127049 * A108547 A319823 A286499

Adjacent sequences: A142882 A142883 A142884 * A142886 A142887 A142888

Keyword

nonn

Author

Roger L. Bagula, Sep 28 2008

Status

approved