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%I #7 Nov 10 2017 11:37:49
%S 31,95,159,223,255,287,351,415,479,543,607,671,735,767,799,863,927,
%T 991,1055,1119,1183,1247,1279,1311,1375,1439,1503,1567,1631,1695,1759,
%U 1791,1823,1887,1951,2047,2079,2143,2207,2271,2303
%N Numbers n such that string 3,7 occurs in the base 8 representation of n but not of n+1.
%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n,8],{3,7}]>0,1,0],{n,2500}],{1,0}][[All,1]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Nov 10 2017 *)
%K nonn,base
%O 1,1
%A _Clark Kimberling_