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A103160 GCD of reversed(n!) and reversed((n+1)!). 0
1, 2, 6, 21, 3, 27, 9, 9, 88263, 9, 99, 594, 198, 99, 99, 99, 99, 99, 99, 9009, 99, 99, 198, 99, 99, 297, 1089, 99, 198, 198, 594, 198, 396, 693, 99, 99, 99, 297, 594, 99, 99, 99, 198, 99, 99, 99, 99, 99, 99, 99, 99, 396, 2772, 99, 99, 99, 396, 693, 693, 99, 99, 99, 99 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Through the first 200 terms, the largest term has 6 digits with the exception of a(99) which has 134 digits. - Harvey P. Dale, Dec 24 2018

LINKS

Table of n, a(n) for n=1..63.

FORMULA

a(n)=GCD[A004153((n+1)!), A004153(n!)]

EXAMPLE

Outstandingly high values arise at n=10^k-1 because

A004153(n)=A004153(n+1), a(n)=rev[n! ], n!-backward-written.

See n=9,99,999, etc..

MATHEMATICA

rd[x_] :=FromDigits[Reverse[IntegerDigits[x]]] Table[GCD[rd[w! ], rd[(w+1)! ]], {w, 1, 100}]

GCD@@#&/@Partition[IntegerReverse[Range[100]!], 2, 1] (* Harvey P. Dale, Dec 24 2018 *)

CROSSREFS

Cf. A000142, A004153.

Sequence in context: A104861 A074859 A162682 * A242819 A126099 A063753

Adjacent sequences:  A103157 A103158 A103159 * A103161 A103162 A103163

KEYWORD

base,nonn

AUTHOR

Labos Elemer, Jan 25 2005

STATUS

approved

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Last modified June 21 19:12 EDT 2021. Contains 345365 sequences. (Running on oeis4.)