A135986 - OEIS

A135986

a(1)=1; a(n) = a(n-1) + d(n) if d(n) > d(n-1); a(n) = a(n-1) - d(n) if d(n) < d(n-1); a(n) = a(n-1) if d(n) = d(n-1), where d = A000005.

1, 3, 3, 6, 4, 8, 6, 10, 7, 11, 9, 15, 13, 17, 17, 22, 20, 26, 24, 30, 26, 26, 24, 32, 29, 33, 33, 39, 37, 45, 43, 49, 45, 45, 45, 54, 52, 56, 56, 64, 62, 70, 68, 74, 74, 70, 68, 78, 75, 81, 77, 83, 81, 89, 85, 93, 89, 89, 87, 99, 97, 101, 107, 114, 110, 118, 116, 122, 118

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..69.

MATHEMATICA

a = {1}; For[n = 2, n < 70, n++, If[DivisorSigma[0, n] > DivisorSigma[0, n - 1], AppendTo[a, a[[ -1]] + DivisorSigma[0, n]], If[DivisorSigma[0, n] < DivisorSigma[ 0, n - 1], AppendTo[a, a[[ -1]] - DivisorSigma[0, n]], AppendTo[a, a[[ -1]]]]]]; a (* Stefan Steinerberger, Oct 20 2008 *)

CROSSREFS

Cf. A000005.

Sequence in context: A023827 A199153 A182627 * A334848 A284614 A349392

Adjacent sequences: A135983 A135984 A135985 * A135987 A135988 A135989

KEYWORD

nonn

AUTHOR

Leroy Quet, Mar 02 2008

EXTENSIONS

More terms from Stefan Steinerberger, Oct 20 2008

STATUS

approved