A347298 - OEIS

%I #25 Nov 28 2024 15:07:19

%S 20,21,22,40,41,42,43,44,60,61,62,63,64,65,66,80,81,82,83,84,85,86,87,

%T 88,100,120,121,122,140,141,142,143,144,160,161,162,163,164,165,166,

%U 180,181,182,183,184,185,186,187,188,200,201,202,203,204,205,206,207,208,209,210,211,212,213,214,215

%N Numbers that contain an even digit d immediately followed by a digit <= d.

%C Conjecture: This is precisely the list of numbers missing from A342042.

%C The conjecture is correct, see A342042 for details. - _Sebastian Karlsson_, Oct 02 2021

%H Paolo Xausa, <a href="/A347298/b347298.txt">Table of n, a(n) for n = 1..10000</a>

%t A347298Q[k_] := Count[Partition[IntegerDigits[k], 2, 1],{i_, j_} /; EvenQ[i] && j <= i] > 0;

%t Select[Range[300], A347298Q] (* _Paolo Xausa_, Nov 28 2024 *)

%o (Python)

%o def ok(n):

%o     s = str(n)

%o     return any(s[i] in "2468" and s[i+1] <= s[i] for i in range(len(s)-1))

%o print([k for k in range(216) if ok(k)]) # _Michael S. Branicky_, Nov 28 2024

%Y Cf. A342042, A377912 (complement).

%K nonn,base

%O 1,1

%A _N. J. A. Sloane_, Aug 26 2021