cp's OEIS Frontend

A281942 Nonnegative numbers whose digits can be formed by typing adjacent keys on a 123-456-789-0XX keypad without repeating a digit.

%I A281942 #30 Jul 08 2018 02:36:33
%S A281942 0,1,2,3,4,5,6,7,8,9,12,14,21,23,25,32,36,41,45,47,52,54,56,58,63,65,
%T A281942 69,70,74,78,85,87,89,96,98,123,125,145,147,214,236,254,256,258,321,
%U A281942 325,365,369,412,452,456,458,470,478,521,523,541,547,563,569,587,589,632,652,654,658,698,741
%N A281942 Nonnegative numbers whose digits can be formed by typing adjacent keys on a 123-456-789-0XX keypad without repeating a digit.
%C A281942 A subsequence of A010784. - _FUNG Cheok Yin_, Jul 05 2018
%H A281942 FUNG Cheok Yin, <a href="/A281942/b281942.txt">Table of n, a(n) for n = 1..725</a>
%e A281942 The keypad is:
%e A281942 +---+---+---+
%e A281942 | 1 | 2 | 3 |
%e A281942 +---+---+---+
%e A281942 | 4 | 5 | 6 |
%e A281942 +---+---+---+
%e A281942 | 7 | 8 | 9 |
%e A281942 +---+---+---+
%e A281942 | 0 | x | x |
%e A281942 +---+---+---+
%e A281942 It is visibly obvious that 470 can be formed on the keypad.
%Y A281942 Cf. A010784, A280593, A280594, A280595, A281943, A215009.
%K A281942 nonn,fini,base,full
%O A281942 1,3
%A A281942 _FUNG Cheok Yin_, Feb 02 2017
%E A281942 Initial 0 added by _N. J. A. Sloane_, Feb 05 2017