cp's OEIS Frontend

A242646 a(n) = concatenation of decimal expansions of powers of 11 (in increasing order).

%I A242646 #13 Sep 12 2014 10:03:04
%S A242646 1,111,111121,1111211331,111121133114641,111121133114641161051,
%T A242646 1111211331146411610511771561,111121133114641161051177156119487171,
%U A242646 111121133114641161051177156119487171214358881,1111211331146411610511771561194871712143588812357947691,111121133114641161051177156119487171214358881235794769125937424601
%N A242646 a(n) = concatenation of decimal expansions of powers of 11 (in increasing order).
%C A242646 a(2) = 111121 is the first prime in this sequence (compare A242645).
%C A242646 There are no further primes through a(100). - _Harvey P. Dale_, Sep 12 2014
%H A242646 Alois P. Heinz, <a href="/A242646/b242646.txt">Table of n, a(n) for n = 0..42</a>
%F A242646 a(n) is the concatenation of 1, 11, 121, 11^3, ... 11^(n-1), 11^n.
%p A242646 a:= proc(n) option remember;
%p A242646       `if`(n=0, 1, parse(cat(a(n-1), 11^n)))
%p A242646     end:
%p A242646 seq(a(n), n=0..10);  # _Alois P. Heinz_, May 24 2014
%t A242646 Module[{nn=15,c},c=IntegerDigits/@(11^Range[0,nn]);Table[FromDigits[ Flatten[ Take[c,n]]],{n,nn+1}]] (* _Harvey P. Dale_, Sep 12 2014 *)
%Y A242646 Cf. A242645.
%K A242646 nonn,base
%O A242646 0,2
%A A242646 _N. J. A. Sloane_, May 23 2014