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A155836 2^(2^n) mod n. 3
0, 0, 1, 0, 1, 4, 4, 0, 4, 6, 3, 4, 9, 2, 1, 0, 1, 16, 4, 16, 4, 16, 3, 16, 21, 16, 13, 16, 16, 16, 8, 0, 4, 18, 11, 16, 33, 16, 22, 16, 37, 16, 4, 20, 31, 6, 21, 16, 4, 16, 1, 16, 42, 52, 36, 16, 28, 54, 20, 16, 57, 16, 4, 0, 61, 16, 21, 52, 64, 16, 12, 16, 4, 16, 31, 24, 4, 16, 73, 16, 40 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

COMMENTS

From the randomness of the graph, it seems likely that every number will eventually occur. a(n)=1 for the n in A094358. When do 5 and 23 occur? The number 14 finally appears at n=34913. a(n) can be computed rapidly using two applications of the powermod function.

LINKS

T. D. Noe, Table of n, a(n) for n = 1..10000

EXAMPLE

a(1941491)=a(43228711)=a(75548489)=5 and a(100867561)=23. See A155886 for the first occurrence of each number. [From T. D. Noe, Jan 31 2009]

MATHEMATICA

Table[e=IntegerExponent[n, 2]; d=n/2^e; k=MultiplicativeOrder[2, d]; r=PowerMod[2, n, k]-e; r=Mod[r, k]; 2^e PowerMod[2, r, d], {n, 100}]

PROG

(PARI) a(n)=my(ph=eulerphi(n)); lift(Mod(2, n)^(ph+lift(Mod(2, ph)^n))) \\ Charles R Greathouse IV, Feb 24 2012

CROSSREFS

A015910 (2^n mod n), A036236.

Sequence in context: A283361 A138518 A290799 * A245971 A279365 A164613

Adjacent sequences:  A155833 A155834 A155835 * A155837 A155838 A155839

KEYWORD

nonn

AUTHOR

T. D. Noe, Jan 28 2009

STATUS

approved

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Last modified December 14 02:56 EST 2018. Contains 318087 sequences. (Running on oeis4.)