A001369 - OEIS

%I #24 Feb 01 2022 01:34:12

%S 1,23,456,7891,1234,567891,123456,78910123,456789101,2345678910,

%T 12345678910,123456789101,2345678910123,45678910123456,

%U 789101234567891,123456789101234,56789101234567891,12345678910123456,7891012345678910123,45678910123456789101

%N Blocks of increasing length using 1,2,3,...,9,10; omit leading 0's.

%C It appears that the first digit repeats 1, 2, 4, 7, 1, 5, 1, 7, 4, 2, 1. - _T. D. Noe_, Apr 05 2011

%H Vincenzo Librandi, <a href="/A001369/b001369.txt">Table of n, a(n) for n = 1..200</a>

%t nn = 20; d = Flatten[Table[{1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 0}, {Ceiling[nn (nn + 1)/22]}]]; Table[e = (n + 1) n/2; s = e - n + 1; FromDigits[d[[s ;; e]]], {n, nn}] (* _T. D. Noe_, Apr 05 2011 *)

%o (PARI) N=[]; k=Mod(-1,10); for(n=1, 20, while(#N<n, N=concat(N, Vec(Str(1+lift(k++))))); print1(eval(concat(vecextract(N, 2^n-1)))", "); N=vecextract(N, Str("^.."n))) \\ _M. F. Hasler_, May 08 2014

%Y Cf. A066547, A007923.

%K nonn,base

%O 1,2

%A _N. J. A. Sloane_