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A277971 a(1) = 1; a(n) > a(n-1) is the smallest number whose name in English contains the first letter of the name of a(n-1). 5
1, 2, 3, 8, 9, 10, 12, 13, 14, 15, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 86, 87, 88, 89, 90, 91 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..68.

MATHEMATICA

names={"one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen", "twenty"};

lst={1}; next[n_]:=next[n]=Module[{pos=Last[lst]+1},

While[StringPosition[names[[pos]], First[Characters[names[[Last[lst]]]]]]=={}&&pos<=Length[names], pos++];

AppendTo[lst, pos]]; seq[n_]:=Nest[next, 1, n]; seq[9]

CROSSREFS

Cf. A277972.

Sequence in context: A309125 A037318 A253317 * A080288 A278560 A217682

Adjacent sequences:  A277968 A277969 A277970 * A277972 A277973 A277974

KEYWORD

easy,nonn,word

AUTHOR

Ivan N. Ianakiev, Nov 07 2016

STATUS

approved

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Last modified October 19 13:01 EDT 2019. Contains 328222 sequences. (Running on oeis4.)