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A053285 Totient of 2^n+1. 0
2, 4, 6, 16, 20, 48, 84, 256, 324, 800, 1364, 3840, 5460, 12544, 19800, 65536, 87380, 186624, 349524, 986880, 1365336, 3345408, 5592404, 16515072, 20250000, 52306176, 84768120, 252645120, 351847488, 760320000, 1431655764, 4288266240 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

FORMULA

a(n)= A000010[A000051(n)]

EXAMPLE

It is a power of 2 iff n is a Fermat prime

CROSSREFS

Cf. A000010, A000225, A051953, A000051.

Sequence in context: A000068 A067662 A001774 * A078148 A076075 A030157

Adjacent sequences:  A053282 A053283 A053284 * A053286 A053287 A053288

KEYWORD

nonn

AUTHOR

Labos E. (labos(AT)ana.sote.hu), Mar 03 2000

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Last modified February 17 21:13 EST 2012. Contains 206085 sequences.