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A103161 GCD of reversed(2^n) and reversed(2^(n+1)). +0
1
2, 4, 1, 1, 23, 1, 1, 1, 1, 4201, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 7, 1, 1, 1, 1, 4, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 19, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 4, 1, 1, 1, 1, 1, 1, 1, 1, 1, 34, 1, 1, 1, 7, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 (list; graph; listen)
OFFSET

1,1

FORMULA

a(n)=GCD[A004094(n), A004094(n+1)]

EXAMPLE

n=10: GCD of backward written powers-of-2 is GCD[4201,8402]=4201=a(10).

MATHEMATICA

rd[x_] :=FromDigits[Reverse[IntegerDigits[x]]] Table[GCD[rd[2^w], rd[2^(w+1)]], {w, 1, 100}]

CROSSREFS

Cf. A000079, A004094.

Sequence in context: A139227 A065626 A096110 this_sequence A030420 A133902 A054708

Adjacent sequences: A103158 A103159 A103160 this_sequence A103162 A103163 A103164

KEYWORD

base,nonn

AUTHOR

Labos E. (labos(AT)ana.sote.hu), Jan 25 2005

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Last modified August 28 22:44 EDT 2008. Contains 143251 sequences.


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