A134070 - OEIS

%I #13 May 07 2023 18:21:30

%S 13,13471118294776123,

%T 134711182947761231993225218431364220735715778934915127244763960364079103682167761271443439204710647114985118604983010349

%N Primes in A130774.

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

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/LucasNumber.html">Lucas Number</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/SmarandacheSequences.html">Smarandache Sequences</a>

%e a(1) = A130774(2) = 13.

%e a(2) = A130774(10) = 13471118294776123.

%e a(3) = A130774(31) = 13471118294776123199322521843136422073571577893491512724476396036407910368216776127144343920471064711498511860498301034.

%t 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 *)

%Y Cf. A000204 (Lucas numbers).

%Y Cf. A130774 (concatenation of Lucas numbers).

%Y Cf. A019523 (concatenation of Fibonacci numbers).

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

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

%Y Cf. A134069 (primes in A038399).

%Y Cf. A134071 (primes in A134072).

%K nonn,base,bref

%O 1,1

%A _Alexander Adamchuk_, Oct 06 2007

%E Edited by _Charles R Greathouse IV_, Apr 24 2010