login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A321533 Numbers k such that sigma(k) = sigma(k+19), where sigma(k) is the sum of the divisors of k. 0
34, 158, 226, 266, 459, 3045, 3518, 3914, 4305, 6236, 8307, 10538, 10574, 18183, 23228, 25346, 25916, 33866, 33998, 48614, 49119, 51015, 56506, 63986, 72267, 82916, 94695, 100634, 144507, 154203, 186879, 269307, 281979, 308926, 358298, 358587, 367802, 380727, 382755, 412796, 474183 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

REFERENCES

J.-M. De Koninck, Ces nombres qui nous fascinent, Entry 34, pp 13, Ellipses, Paris 2008.

LINKS

Table of n, a(n) for n=1..41.

EXAMPLE

sigma(34) = sigma(34+19) = 54.

MATHEMATICA

Select[Range[10^6], DivisorSigma[1, #] == DivisorSigma[1, # + 19] &] (* Vincenzo Librandi, Nov 13 2018 *)

PROG

(PARI) isok(n) = sigma(n+19) == sigma(n); \\ Michel Marcus, Nov 13 2018

(Magma) [n: n in [1..2*10^6] | SumOfDivisors(n) eq SumOfDivisors(n + 19)]; // Vincenzo Librandi, Nov 13 2018

CROSSREFS

Cf. A000203.

Sequence in context: A167241 A028470 A221806 * A345157 A345126 A212407

Adjacent sequences:  A321530 A321531 A321532 * A321534 A321535 A321536

KEYWORD

nonn

AUTHOR

Jud McCranie, Nov 12 2018

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 29 09:23 EDT 2022. Contains 357088 sequences. (Running on oeis4.)