A134070 Primes in A130774.

13, 13471118294776123, 134711182947761231993225218431364220735715778934915127244763960364079103682167761271443439204710647114985118604983010349

Offset: 1

Author

Alexander Adamchuk, Oct 06 2007

Keywords

• nonn
• base
• bref
• hard

Comments

A130774 = {1, 13, 134, 1347, 134711, 13471118, 1347111829, 134711182947, 13471118294776, 13471118294776123, ...} = Concatenate Lucas numbers. Indices of prime terms in A130774 are {2, 10, 31, ...}.

a(4) > A130774(500) = 1.347...*10^26425, if it exists. - Amiram Eldar, Jul 17 2025

Examples

			a(1) = A130774(2) = 13.
a(2) = A130774(10) = 13471118294776123.
a(3) = A130774(31) = 13471118294776123199322521843136422073571577893491512724476396036407910368216776127144343920471064711498511860498301034.
		

Links

• Eric Weisstein's World of Mathematics, Lucas Number.
• Eric Weisstein's World of Mathematics, Smarandache Sequences.

Crossrefs

Cf. A000204 (Lucas numbers).

Cf. A130774 (concatenation of Lucas numbers).

Cf. A019523 (concatenation of Fibonacci numbers).

Cf. A038399 (concatenation of first n nonzero Fibonacci numbers in reverse order).

Cf. A134072 (concatenation of A000204 Lucas numbers (beginning at 1) in reverse order).

Cf. A134069 (primes in A038399).

Cf. A134071 (primes in A134072).

Programs

Mathematica

Select[Module[{nn=40,ll},ll=LucasL[Range[nn]];Table[FromDigits[Flatten[IntegerDigits/@Take[ll,n]]],{n,nn}]],PrimeQ] (* Harvey P. Dale, May 07 2023 *)

Extensions

Edited by Charles R Greathouse IV, Apr 24 2010