A239363 Numbers n such that phi(n+1)-phi(n) = n/2.

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

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 A358000

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