|
%I #21 Apr 22 2021 22:09:21
%S 0,1,2,3,4,5,7,8,9,10,11,12,13,14,15,1,17,18,19,20,21,22,23,24,25,2,
%T 27,28,29,30,31,32,33,34,35,3,37,38,39,40,41,42,43,44,45,4,47,48,49,
%U 50,51,52,53,54,55,5,57,58,59,0,1,2,3,4,5,7,8,9,70,71,72,73,74,75,7
%N Delete all 6's from the sequence of nonnegative integers.
%t d6[n_]:=Module[{c=DeleteCases[IntegerDigits[n],6]},If[c=={},Nothing, FromDigits[ c]]]; Array[d6,80,0] (* _Harvey P. Dale_, Oct 09 2017 *)
%o (Python)
%o def A004725(n):
%o l = len(str(n))
%o m = 2*(10**l-1)//3
%o k = n + l - int(n+l < m)
%o return 5 if k == m else int(str(k).replace('6','')) # _Chai Wah Wu_, Apr 20 2021
%Y Cf. A004719, A004720, A004721, A004722, A004723, A004724, A004726, A004727, A004728.
%K base,nonn
%O 0,3
%A _N. J. A. Sloane_
|
