OFFSET
1,1
COMMENTS
The first two odd elements are a(49) = 8415 and a(107) = 31815.- Robert Israel, Jan 16 2020
LINKS
Robert Israel, Table of n, a(n) for n = 1..1400
MAPLE
filter:= proc(k) numtheory:-sigma(k)-convert(convert(k, base, 10), `+`)=2*k end proc:
select(filter, [$1..10000]); # Robert Israel, Jan 16 2020
MATHEMATICA
Select[Range[10^4], DivisorSigma[1, #] - Plus @@ IntegerDigits[#] == 2 # &] (* Amiram Eldar, Jan 11 2020 *)
PROG
(PARI) isok(k) = sigma(k) - k - sumdigits(k) == k; \\ Michel Marcus, Jan 11 2020
(Magma) [k:k in [1..8250]| DivisorSigma(1, k) eq 2*k+&+Intseq(k)]; // Marius A. Burtea, Jan 11 2020
CROSSREFS
KEYWORD
nonn,base,less
AUTHOR
Joseph E. Marrow, Jan 08 2020
STATUS
approved