login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A054004 Numbers n such that n and n+1 have the same number and sum of divisors. 12
14, 1334, 1634, 2685, 33998, 42818, 64665, 84134, 109214, 122073, 166934, 289454, 383594, 440013, 544334, 605985, 649154, 655005, 792855, 1642154, 2284814, 2305557, 2913105, 3571905, 3682622, 4701537, 5181045, 6431732 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

T. D. Noe, Table of n, a(n) for n=1..967

EXAMPLE

Divisors of 14 = {1, 2, 7, 14}, divisors of 15 = {1, 3, 5, 15}, both have four divisors and sum=24.

MATHEMATICA

Select[Range[100000], DivisorSigma[0, #] == DivisorSigma[0, # + 1] && DivisorSigma[1, #] == DivisorSigma[1, # + 1] &] (* Jayanta Basu, Mar 20 2013 *)

CROSSREFS

Cf. A000005, A000203, A002961, A005237, A053249, A054005, A054006, A054007.

Sequence in context: A137603 A160107 A322256 * A280087 A240703 A240640

Adjacent sequences:  A054001 A054002 A054003 * A054005 A054006 A054007

KEYWORD

nonn

AUTHOR

Asher Auel (asher.auel(AT)reed.edu), Jan 12 2000

EXTENSIONS

More terms from Jud McCranie, Jun 02 2000

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 15 18:40 EDT 2021. Contains 348033 sequences. (Running on oeis4.)