A282637 a(1) = 1. a(n) is the smallest unlisted natural number whose name in (American) English ends with the letter a(n-1) starts with, and makes the sequence extendable.
1, 2, 8, 3, 28, 38, 88, 9, 10, 98, 11, 12, 108, 22, 128, 32, 138, 82, 21, 148, 92, 13, 158, 102, 122, 132, 142, 152, 162, 172, 182, 192, 202, 168, 222, 178, 232, 188, 242, 198, 252, 208, 228, 238, 248, 258, 268, 278, 288, 298, 308, 328, 338, 348, 358, 368, 378, 388, 398, 808, 23, 828, 25, 838, 29, 848
Offset: 1
Examples
38 is followed by 88 as 48, 58, 68 and 78 cannot make the sequence extendable.
Programs
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Mathematica
names = StringReplace[ IntegerName /@ Range[1000], {"\[Hyphen]" -> "", " " -> ""}]; lst = {1}; next[n_] := next[n] = Module[{pos = Complement[Range[Length[names]], lst], i = 1}, While[ Or[ And[ First[Characters[names[[Last[lst]]]]] != Last[Characters[names[[pos[[i]]]]]], pos[[i]] <= Length[names] ], MemberQ[{"f", "s"}, First[Characters[names[[pos[[i]]]]]]] == True ], i++ ]; AppendTo[lst, pos[[i]]] ]; seq[n_] := Nest[next, 1, n]; seq[65]
Comments