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A239363 Numbers n such that phi(n+1)-phi(n) = n/2. 1
2, 4, 16, 24, 216, 256, 4960, 10648, 65536, 195112, 1191016, 7544800, 11530464, 12705504, 45882712, 55742968, 179883264, 946966168, 2106997768, 2289529432, 2548895896, 3056745600, 3482123272, 7756683264, 10735357816, 15920801280, 26946035992, 46827274240 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Giovanni Resta, Table of n, a(n) for n = 1..39 (terms < 10^12)

EXAMPLE

phi(217) = 180, phi(216) = 72, and 180-72 = 108, which is 216/2.

MAPLE

with(numtheory); P:=proc(q) local n;

for n from 1 to q do if phi(n+1)-phi(n)=n/2 then print(n);

fi; od; end: P(10^9);

CROSSREFS

Cf. A000010.

Sequence in context: A324211 A059622 A131475 * A045541 A234639 A275674

Adjacent sequences:  A239360 A239361 A239362 * A239364 A239365 A239366

KEYWORD

nonn

AUTHOR

Paolo P. Lava, Mar 17 2014

EXTENSIONS

a(13)-a(27) from Giovanni Resta, Mar 17 2014

STATUS

approved

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Last modified September 19 03:31 EDT 2021. Contains 347550 sequences. (Running on oeis4.)