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Search: id:A069535
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| A069535 |
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Treated as strings, n and its reversal are substrings of n!. |
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+0
9
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| 1, 2, 4, 20, 30, 33, 42, 44, 45, 51, 60, 67, 72, 75, 78, 79, 80, 81, 82, 84, 88, 91, 94, 95, 97, 98, 99, 116, 140, 141, 166, 170, 180, 188, 198, 200, 202, 210, 222, 228, 231, 238, 252, 261, 264, 265, 272, 285, 286, 292, 293, 297, 311, 313, 315, 317, 321
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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This is the sequence of "fixated points" (cf. A068588) of f(n) = n!.
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LINKS
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Pe, J. Fixated Points of Arithmetical Functions
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EXAMPLE
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42! = 1405006117752879898543142606244511569936384000000000, which contains both 42 and 24 as substrings. Hence 42 is a term of the sequence.
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MATHEMATICA
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r = {}; Do[m = n!; s = ToString[m]; If[ StringPosition[s, ToString[n]] != {} && StringPosition[s, ToString[ FromDigits[ Reverse[ IntegerDigits[n]]]]] != {}, r = Append[r, n]], {n, 1, 321}]; r
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CROSSREFS
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Cf. A068588.
Sequence in context: A133521 A122158 A033180 this_sequence A108866 A059206 A052004
Adjacent sequences: A069532 A069533 A069534 this_sequence A069536 A069537 A069538
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KEYWORD
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base,nonn
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AUTHOR
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Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Apr 16 2002
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EXTENSIONS
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Edited and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Apr 19 2002
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