OFFSET
1,1
COMMENTS
The first time a pair ordered by its first element is not adjacent is x = 16104, y = 16632 which correspond to a(11) and a(13), respectively.
LINKS
Paolo P. Lava, Table of n, a(n) for n = 1..500
EXAMPLE
(1+e)-sigma(366) = 378 and (1+e)-sigma(378) = 366.
MAPLE
with(numtheory): T:=proc(n) local a, d, p, e, s, sp; a:=1;
for d in ifactors(n)[2] do p:=op(1, d); e:= op(2, d); sp:=1;
for s in divisors(e) do sp:=sp+p^s; od: a:=a*sp; od: a; end:
P:=proc(q) local n, x, y; for n from 1 to q do x:=T(n)-n; y:=T(x)-x;
if n=y and x<>y then print(n); fi; od; end: P(10^10);
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Paolo P. Lava, Jun 10 2016
STATUS
approved