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A367613
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Numbers with exactly one comma-child.
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1
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1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 16, 17, 19, 20, 21, 22, 23, 24, 25, 26, 28, 29, 30, 31, 32, 34, 35, 37, 38, 39, 40, 41, 42, 43, 44, 46, 47, 48, 49, 50, 51, 53, 55, 56, 57, 58, 59, 60, 61, 62, 64, 65, 66, 67, 68, 69, 70, 73, 74, 75, 76, 77, 78, 79, 80, 82, 83
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,2
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COMMENTS
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See A367338 for definition of comma-child.
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LINKS
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Eric Angelini, Michael S. Branicky, Giovanni Resta, N. J. A. Sloane, and David W. Wilson, The Comma Sequence: A Simple Sequence With Bizarre Properties, arXiv:2401.14346, Youtube
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MATHEMATICA
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fQ[n_]:=Module[{k=n+10*Last[IntegerDigits[n]]+Range[9]}, Length[Select[k, #-n==FromDigits[{Last[IntegerDigits[n]], First[IntegerDigits[#]]}]&]]]==1;
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PROG
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(Python)
def ok(n):
m = n + 10*(n%10)
return len([m+y for y in range(1, 10) if int(str(m+y)[0]) == y]) == 1
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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