A015821 - OEIS

A015821

Numbers k such that phi(k + 5) | sigma(k).

3, 7, 15, 22, 23, 30, 35, 44, 47, 51, 56, 71, 88, 95, 135, 140, 153, 155, 167, 207, 239, 263, 280, 310, 311, 368, 383, 385, 395, 431, 503, 506, 599, 635, 646, 647, 658, 719, 839, 887, 911, 920, 995, 1012, 1023, 1045, 1078, 1080, 1103, 1131, 1185, 1223, 1309

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

MATHEMATICA

Select[Range[10000], Divisible[DivisorSigma[1, #], EulerPhi[5 + #]] &] (* David Nacin, Mar 01 2012 *)

CROSSREFS

Sequence in context: A320026 A146435 A046932 * A229527 A091711 A103007

Adjacent sequences: A015818 A015819 A015820 * A015822 A015823 A015824

KEYWORD

nonn

AUTHOR

Robert G. Wilson v

STATUS

approved