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A069535 Treated as strings, n and its reversal are substrings of n!. 7
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; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

This is the sequence of "fixated points" (cf. A068588) of f(n) = n!.

LINKS

Table of n, a(n) for n=1..57.

Pe, J. Fixated Points of Arithmetical Functions

EXAMPLE

42! = 1405006117752879898543142606244511569936384000000000, which contains both 42 and 24 as substrings. Hence 42 is a term of the sequence.

MATHEMATICA

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

CROSSREFS

Cf. A068588.

Sequence in context: A215815 A295826 A201502 * A108866 A259122 A059206

Adjacent sequences:  A069532 A069533 A069534 * A069536 A069537 A069538

KEYWORD

base,nonn

AUTHOR

Joseph L. Pe, Apr 16 2002

EXTENSIONS

Edited and extended by Robert G. Wilson v, Apr 19 2002

STATUS

approved

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Last modified August 18 01:19 EDT 2019. Contains 326059 sequences. (Running on oeis4.)