A093100 - OEIS

%I #9 Aug 04 2014 18:48:37

%S 13,34,47,711,118,182,829,2910,91011,101110,11101,11012,10122,1221,

%T 2213,2134,1343,3434,4347,3477,4777,77711,771114,7111414,1114148,

%U 1141482,1414822,4148225,1482255,4822555,82255512,225551210,255512104,555121047

%N "Lucas-digits": start with "13", append sum of first 2 digits to the preceding number, drop first digit.

%C There are only 7 primes in the first 1000 terms of this sequence.  The first 6 primes are 13, 47, 829, 2213, 77711, and 174111811681183993.  The 7th prime, a(920), has 214 digits. - _Harvey P. Dale_, Aug 04 2014

%H Harvey P. Dale, <a href="/A093100/b093100.txt">Table of n, a(n) for n = 1..1000</a>

%e a(4): sum of first 2 digits of a(3)=11, append 11 to 47 and get 4711, drop first digit and get 711.

%t ld[n_]:=Module[{idn=IntegerDigits[n]},FromDigits[Rest[Join[ idn, IntegerDigits[ Total[ Take[idn,2]]]]]]]; NestList[ld,13,40] (* _Harvey P. Dale_, Aug 04 2014 *)

%Y Cf. A093086-A093099.

%K nonn,base

%O 1,1

%A _Bodo Zinser_, Mar 22 2004