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A275590
When written in English, the terms of the sequence with an odd number of letters form blocks whose sizes are given by the sequence itself.
0
1, 4, 2, 3, 6, 7, 5, 8, 10, 9, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 26, 27, 28, 24, 25, 29, 30, 31, 32, 33, 36, 37, 38, 40, 34, 35, 39, 41, 42, 43, 44, 45, 49, 50, 54, 46, 47, 48, 51, 52, 53, 55, 59, 60, 64, 65, 69, 70, 74, 56, 57, 58, 61, 62, 63, 66, 67, 68, 71, 72, 73, 75, 79, 81, 82, 83, 86, 87, 88, 91, 92, 76, 77, 78, 80, 84, 85, 89, 90, 93
OFFSET
1,2
COMMENTS
The sequence is started with a(1) = "ONE" and always extended with the smallest integer not yet used whose name in English does not lead to a contradiction.
The sequence is a permutation of the natural numbers.
The convention adopted here is to write the English number-names like "101" as ONE HUNDRED ONE and not ONE HUNDRED AND ONE (which would have produced a different sequence).
EXAMPLE
The blocks of "odd-words" are written in UPPER CASE letters and enclosed in parentheses; the successive block-sizes are 1, 4, 2, 3, 6, 7, ... which reproduces the sequence itself:
(ONE), four, (TWO, THREE, SIX, SEVEN), five, (EIGHT, TEN), nine, eleven, twelve, thirteen, fourteen, (FIFTEEN, SIXTEEN, SEVENTEEN), eighteen, nineteen, twenty, (TWENTY-ONE, TWENTY-TWO, TWENTY-THREE, TWENTY-SIX, TWENTY-SEVEN, TWENTY-EIGHT), twenty-four, twenty-five, twenty-nine, thirty, (THIRTY-ONE, THIRTY-TWO, THIRTY-THREE, THIRTY-SIX, THIRTY-SEVEN, THIRTY-EIGHT, FORTY), thirty-four, ...
CROSSREFS
Sequence in context: A282865 A377137 A241051 * A338844 A333406 A083181
KEYWORD
nonn,word,base
AUTHOR
Eric Angelini, Aug 02 2016
STATUS
approved