A322094 - OEIS

%I #17 Nov 27 2018 03:11:33

%S 1,2,3,4,5,6,7,8,9,10,11,1,13,14,15,16,17,18,19,20,21,22,1,24,25,26,

%T 27,28,29,30,1,32,33,1,35,36,37,38,39,40,1,1,43,44,1,46,47,48,49,50,1,

%U 1,1,54,55,1,57,58,59,60,1,1,1,1,65,66,1,68,69,70,1,1

%N a(n) = number of occurrences of the decimal representation of n in the concatenation of all terms preceding a(n), or n if there are no such occurrences.

%C In the definition of the sequence, consider the number of occurrences of string s in string t to be the number of positions within t that have a perfect match with the digits in s. Thus the number of occurrences of 11 in 1111 is 3 and not 2.

%H John Mason, <a href="/A322094/b322094.txt">Table of n, a(n) for n = 1..10000</a>

%e a(12) is 1 as there is one occurrence of "12" in the string formed by concatenating a(1) through a(11).

%t FromDigits /@ Nest[Function[{a, n}, Append[a, If[# == 0, IntegerDigits@ n, IntegerDigits@ #] &@ SequenceCount[Join @@ a, IntegerDigits@ n]]] @@ {#, Length@ # + 1} &, {{1}}, 67] (* _Michael De Vlieger_, Nov 26 2018 *)

%Y Cf. A048991, A048992.

%K nonn,base

%O 1,2

%A _John Mason_, Nov 26 2018