A274333 Indices of Lucas numbers having exactly one primitive prime factor.

0, 2, 4, 5, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 24, 26, 27, 28, 30, 31, 33, 36, 37, 38, 41, 47, 49, 53, 54, 56, 61, 62, 66, 68, 70, 71, 72, 76, 78, 79, 80, 86, 90, 91, 96, 110, 113, 117, 120, 121, 136, 140, 144, 164, 168, 172, 178, 202, 203

Offset

1,2

Comments

0 together with numbers n such that A086600(n) = 1, except if n = 3.

The only primes in this sequence are the primes numbers in A001606, which gives the indices of prime Lucas numbers.

Links

Arkadiusz Wesolowski, Table of n, a(n) for n = 1..102

Prog

(Magma) lst:=[]; pr:=1; for n in [0..203] do pd:=PrimeDivisors(Lucas(n)); d:=1; t:=0; for c in [1..#pd] do f:=pd[c]; if Gcd(pr, f) eq 1 then t+:=1; else d:=d*f; end if; end for; if t eq 1 then Append(~lst, n); end if; pr:=pr*Truncate(Lucas(n)/d); end for; lst;

Crossrefs

Cf. A000032, A001606, A058036, A086600.

Sequence in context: A023962 A094562 A178344 * A039241 A000394 A039184

Adjacent sequences: A274330 A274331 A274332 * A274334 A274335 A274336

Keyword

nonn

Author

Arkadiusz Wesolowski, Jun 22 2016

Status

approved