%I #29 Feb 05 2024 09:17:05

%S 1,0,0,0,1,3,0,0,1,1,2,0,0,0,0,2,1,0,2,0,2,0,0,1,2,0,0,1,0,0,2,2,2,0,

%T 3,1,1,0,1,0,1,1,1,0,3,1,0,1,1,1,1,2,2,1,0,1,1,0,1,3,2,0,1,1,0,2,0,0,

%U 0,0,1,0,1,1,2,5,2,1,2,0,3,3,2,1,0,1,0,0,0,0,5,1,3,4,2,2,1,1,10

%N Number of (potentially overlapping) occurrences of n in the decimal representation of n^n.

%C Differs from A236314 at n=99.

%H Scott R. Shannon, <a href="/A236322/b236322.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..999 from Christian Perfect).

%t a[n_] := Length[StringPosition @@ ToString /@ {n^n, n}]; Array[a, 99] (* _Giovanni Resta_, Jan 22 2014 *)

%o (Python)

%o from itertools import count

%o def occurrences(string, sub):

%o ....count = start = 0

%o ....while True:

%o ........start = string.find(sub, start) + 1

%o ........if start > 0:

%o ............count+=1

%o ........else:

%o ............return count

%o def a(n):

%o ....return occurrences(str(n**n),str(n))

%o (PARI) a(n) = my(m=Mod(n,10^#Str(n)));(m==n=n^n)+sum(i=0,1+log(n)/log(10),m==n\=10) \\ - _M. F. Hasler_, Jan 23 2014

%Y A049329 lists n where a(n) is nonzero.

%Y Non-overlapping occurrences are counted by A236314.

%K base,nonn

%O 1,6

%A _Christian Perfect_, Jan 22 2014