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!)
A282255 Least k > 0 such that sigma(n) divides sigma(n+k). 1
1, 3, 3, 8, 1, 5, 7, 16, 9, 7, 3, 16, 7, 1, 8, 9, 5, 27, 5, 6, 10, 8, 7, 14, 23, 15, 27, 11, 9, 16, 11, 36, 2, 19, 7, 81, 37, 16, 21, 18, 3, 20, 43, 16, 45, 5, 15, 27, 25, 30, 4, 45, 32, 2, 11, 31, 22, 30, 28, 18, 14, 7, 40, 128, 13, 4, 67, 14, 8, 24, 23, 189, 73, 39, 37, 32, 28, 14, 35, 42, 81, 14, 9, 40, 17, 45 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Altug Alkan, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = A069789(n) - n. - Michel Marcus, Feb 10 2017

EXAMPLE

a(4) = 8 because sigma(4) = 7 divides sigma(4 + 8) = 28 and 8 is the least positive number with this property.

MATHEMATICA

Table[k = 1; While[! Divisible[DivisorSigma[1, n + k], DivisorSigma[1, n]], k++]; k, {n, 120}] (* Michael De Vlieger, Feb 10 2017 *)

PROG

(PARI) a(n) = my(k = 1); while (sigma(n+k) % sigma(n) != 0, k++); k;

CROSSREFS

Cf. A000203, A069789.

Sequence in context: A079073 A165507 A212636 * A164040 A154178 A276800

Adjacent sequences:  A282252 A282253 A282254 * A282256 A282257 A282258

KEYWORD

nonn

AUTHOR

Altug Alkan, Feb 10 2017

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 February 21 20:40 EST 2020. Contains 332111 sequences. (Running on oeis4.)