cp's OEIS Frontend

A342846 Number of distinct odd numbers visible as proper substrings of n.

%I A342846 #10 Mar 26 2021 06:32:57
%S A342846 0,0,0,0,0,0,0,0,0,1,1,1,2,1,2,1,2,1,2,0,1,0,1,0,1,0,1,0,1,1,2,1,1,1,
%T A342846 2,1,2,1,2,0,1,0,1,0,1,0,1,0,1,1,2,1,2,1,1,1,2,1,2,0,1,0,1,0,1,0,1,0,
%U A342846 1,1,2,1,2,1,2,1,1,1,2,0,1,0,1,0,1,0,1,0,1,1,2,1,2,1,2,1,2,1,1,1,1,1,2,1,2
%N A342846 Number of distinct odd numbers visible as proper substrings of n.
%C A342846 Here substrings are contiguous.
%C A342846 a(A164766(n)) = n and a(m) <> n for m < A164766(n); a(A014263(n)) = 0. - _Reinhard Zumkeller_, Aug 25 2009
%H A342846 Reinhard Zumkeller, <a href="/A342846/b342846.txt">Table of n, a(n) for n = 1..20000</a>
%H A342846 Sean A. Irvine, <a href="https://github.com/archmageirvine/joeis/blob/master/src/irvine/oeis/a342/A342846.java">Java program</a> (github)
%e A342846 a(10)=1 since we can see 1 as a proper substring of 10.
%e A342846 a(105)=2 since we can see 1, 5.
%e A342846 a(132)=3 because we can see 1, 3, 13.
%o A342846 (Haskell)
%o A342846 import Data.List (isInfixOf)
%o A342846 a045888 n = length $ filter (`isInfixOf` (show n)) $ map show [1, 3..n-1]
%o A342846 -- Reinhard Zumkeller, Jul 19 2011
%o A342846 (Python)
%o A342846 def a(n):
%o A342846   s, eset = str(n), set()
%o A342846   for i in range(len(s)):
%o A342846     for j in range(i+1, len(s)+1):
%o A342846       if s[j-1] in "13579" and j-i < len(s): # odd and proper substring
%o A342846         eset.add(int(s[i:j]))
%o A342846   return len(eset)
%o A342846 print([a(n) for n in range(1, 105)]) # _Michael S. Branicky_, Mar 24 2021
%Y A342846 Cf. A045887, A045888, A342845.
%K A342846 nonn,base,easy
%O A342846 1,13
%A A342846 _Sean A. Irvine_, Mar 24 2021