%I #7 Jul 26 2021 10:21:47
%S 16,41,66,84,91,116,141,166,191,209,216,241,266,291,316,334,341,366,
%T 391,424,441,459,466,491,516,541,566,584,591,616,641,666,691,709,716,
%U 741,766,791,816,834,841,866,891,916,941,959,966
%N Numbers n such that string 3,1 occurs in the base 5 representation of n but not of n+1.
%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n,5],{3,1}]>0,1,0],{n,1000}],{1,0}][[All,1]] (* _Harvey P. Dale_, Jul 26 2021 *)
%K nonn,base
%O 1,1
%A _Clark Kimberling_