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A090128 Distinct values of sigma(k), the sum of divisors, in order of appearance as n grows. 1
1, 3, 4, 7, 6, 12, 8, 15, 13, 18, 28, 14, 24, 31, 39, 20, 42, 32, 36, 60, 40, 56, 30, 72, 63, 48, 54, 91, 38, 90, 96, 44, 84, 78, 124, 57, 93, 98, 120, 80, 168, 62, 104, 127, 144, 68, 126, 195, 74, 114, 140, 186, 121, 224, 108, 132, 180, 234, 112, 128, 252, 171, 156, 217 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Giovanni Resta, Table of n, a(n) for n = 1..10000

MATHEMATICA

t = Table[DivisorSigma[1, w], {w, 100}]; u = Union[t]; uu = Union@ Table[ Min[ Flatten[ Position[t, u[[j]]]]], {j, Length[u]}]; Table[ t[[uu[[j]]]], {j, Length[uu]}]

DeleteDuplicates[DivisorSigma[1, Range[100]]] (* Harvey P. Dale, Dec 01 2018 *)

CROSSREFS

Cf. A053212, A090127.

Sequence in context: A324545 A003979 A084250 * A086293 A337708 A348944

Adjacent sequences:  A090125 A090126 A090127 * A090129 A090130 A090131

KEYWORD

nonn

AUTHOR

Labos Elemer, Jan 16 2004

STATUS

approved

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Last modified May 20 16:35 EDT 2022. Contains 353875 sequences. (Running on oeis4.)