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!)
A063981 Numbers n such that t(n) = sigma(n) - n, where t(n) = A008472(n+1) - A008472(n). 0
2, 4, 9, 16, 81, 85, 256, 931, 65536, 4599097, 6309263, 16905401, 43046721, 54116239, 68229263, 98643563, 208288271, 222933913, 226461649, 230893123, 280399957, 381001633, 412016873, 417814973, 485674237, 620336281, 736284077 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..27.

MATHEMATICA

a = 0; b = 0; Do[a = b; b = Apply[ Plus, Transpose[ FactorInteger[n + 1]] [[1]]]; If[ b - a == DivisorSigma[1, n] - n, Print[n]], {n, 1, 2*10^7} ]

CROSSREFS

Cf. A008472, A001065.

Sequence in context: A344265 A249902 A060401 * A131095 A207813 A136379

Adjacent sequences:  A063978 A063979 A063980 * A063982 A063983 A063984

KEYWORD

nonn

AUTHOR

Jason Earls, Sep 05 2001

EXTENSIONS

More terms from Robert G. Wilson v, Oct 05 2001

a(14)-a(27) from Donovan Johnson, Oct 13 2009

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 June 19 22:51 EDT 2021. Contains 345152 sequences. (Running on oeis4.)