A053227 First differences of sigma(n) that are negative.

1, 4, 2, 6, 14, 13, 19, 10, 12, 29, 2, 26, 40, 15, 6, 53, 4, 48, 52, 6, 6, 24, 67, 21, 44, 48, 40, 30, 106, 43, 76, 30, 72, 121, 44, 88, 65, 42, 116, 12, 90, 122, 40, 24, 154, 15, 115, 112, 18, 30, 54, 170, 64, 134, 96, 28, 2, 36, 227, 18, 68, 184, 79, 120, 176, 132, 148

Offset

1,2

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Formula

a(n) = A053222(A053226(n))

Maple

with(numtheory): seq( `if`((sigma(i) > sigma(i+1)), (sigma(i) - sigma(i+1)), print( )), i=1..200);

Mathematica

Abs[Select[Differences[DivisorSigma[1, Range[200]]], #<0&]] (* Harvey P. Dale, Apr 17 2022 *)

Crossrefs

Cf. A000203, A053222, A053225.

Sequence in context: A019610 A344792 A058613 * A083760 A073597 A099507

Adjacent sequences: A053224 A053225 A053226 * A053228 A053229 A053230

Keyword

nonn

Author

Asher Auel, Jan 06 2000

Status

approved