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A339774
a(n) is the least k such that 3^k == A047471(n) (mod 2^A047471(n)).
1
0, 1, 2, 39, 23988, 2685, 1079830, 3, 1798749736, 7936950713, 314244766442, 895397198495, 65283613526364, 203550894972341, 27025091041430142, 54487836217255419, 2756442714229679952, 34856858877609547377, 2262552012902592868562, 4616799241038411627031, 4, 116433218705414728492013
OFFSET
1,3
COMMENTS
For n >= 3, 3^x == y (mod 2^n) has solutions x if and only if y is in A047471.
LINKS
FORMULA
a((3^k - (-1)^k)/4 + 1) = k.
EXAMPLE
a(4) = 39 because A047471(4) = 11 and 3^39 == 11 (mod 2^11).
MAPLE
f:= proc(n) local k, v;
v:= subs(msolve(3^k=n, 2^n), k);
subs(op(indets(v))=0, v)
end proc:
seq(seq(f(8*i+j), j=[1, 3]), i=0..10);
CROSSREFS
Cf. A047471.
Sequence in context: A274574 A212615 A247878 * A232086 A356683 A047660
KEYWORD
nonn
AUTHOR
J. M. Bergot and Robert Israel, Dec 16 2020
STATUS
approved