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A053215 Sum of divisors of those numbers n such that n and n+1 have the same sum of divisors. 5
24, 312, 1440, 2160, 2688, 2640, 4320, 4464, 7644, 22932, 28314, 29040, 34560, 37440, 51840, 56160, 65280, 100800, 115200, 114912, 120960, 120960, 138240, 153216, 194400, 168960, 178560, 186048, 207360, 221184, 244800, 280800, 276480 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10135 (from the b-file at A002961; terms 1..4804 from T. D. Noe)

FORMULA

a(n) = sigma(A002961(n))

MATHEMATICA

Transpose[Select[{DivisorSigma[1, First[#]], DivisorSigma[1, Last[#]]}&/@ Partition[Range[280000], 2, 1], First[#]==Last[#]&]][[1]] (* Harvey P. Dale, May 07 2012 *)

DivisorSigma[1, #]&/@SequencePosition[DivisorSigma[1, Range[280000]], {x_, x_}][[All, 1]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Sep 21 2017 *)

CROSSREFS

Cf. A000203, A002961, A053249.

Sequence in context: A125436 A096821 A168303 * A290939 A004413 A319554

Adjacent sequences:  A053212 A053213 A053214 * A053216 A053217 A053218

KEYWORD

nonn

AUTHOR

Asher Auel (asher.auel(AT)reed.edu), Jan 11 2000

STATUS

approved

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Last modified October 15 07:38 EDT 2019. Contains 328026 sequences. (Running on oeis4.)