OFFSET
1,1
LINKS
Donovan Johnson, Table of n, a(n) for n = 1..300
MATHEMATICA
Flatten[Position[Partition[DivisorSigma[1, Range[5200000]], 4, 1], {x_, y_, z_, x_}]] (* Harvey P. Dale, Aug 08 2011 *)
Select[Range[6000000], DivisorSigma[1, #]==DivisorSigma[1, # + 3] &] (* Vincenzo Librandi, Mar 10 2014 *)
SequencePosition[DivisorSigma[1, Range[5150000]], {x_, _, _, x_}][[;; , 1]] (* Harvey P. Dale, Dec 01 2024 *)
PROG
(PARI) is(n)=sigma(n)==sigma(n+3) \\ Charles R Greathouse IV, Mar 09 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved