A066519 Gaps between successive numbers with an anti-divisor class sum of zero.

1, 1, 3, 3, 6, 2, 4, 7, 2, 6, 7, 3, 1, 4, 3, 8, 7, 2, 1, 3, 5, 10, 2, 1, 3, 3, 2, 1, 5, 1, 1, 1, 4, 4, 2, 2, 2, 9, 2, 6, 9, 1, 1, 4, 4, 1, 3, 6, 1, 3, 22, 1, 9, 1, 1, 2, 2, 4, 7, 3, 5, 4, 1, 2, 20, 1, 2, 6, 1, 4, 4, 9, 5, 1, 4, 5, 2, 7, 8, 2, 2, 9, 2, 2, 1, 5, 3, 1, 4, 1, 12, 16, 13, 5, 1, 9, 2, 1, 3, 3

Offset

1,3

Comments

See A066272 for definition of anti-divisor.

Links

Table of n, a(n) for n=1..100.

Jon Perry, Class sums

Example

f(1)=f(2)=f(3)=0, f(4)=1, f(5)=-1, f(6)=0, so the first 3 gaps are 1, 1, 3.

Mathematica

a[ n_ ] := Sum[ Which[ Mod[ n, d ]==(d-1)/2, -1, Mod[ n, d ]==(d+1)/2, 1, True, 0 ], {d, 2, n-1} ]; z=Select[ Range[ 1, 500 ], a[ # ]==0& ]; Drop[ z, 1 ]-Drop[ z, -1 ]

Crossrefs

Cf. A066518.

Sequence in context: A342512 A205548 A010609 * A236258 A105158 A020813

Adjacent sequences: A066516 A066517 A066518 * A066520 A066521 A066522

Keyword

nonn

Author

Jon Perry, Jan 06 2002

Extensions

Edited by Dean Hickerson, Jan 17 2002

Status

approved