OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..120
MATHEMATICA
s[n_] := Module[{d = Reverse[Select[Divisors[n], CoprimeQ[#, n/#] &]]}, Total[(-1)^(Range[Length[d]] + 1)*d]]; Select[Range[10^5], s[#] == s[# + 1] &]
PROG
(PARI) s(n) = {my(d = Vecrev(select(x->(gcd(x, n/x) == 1), divisors(n)))); sum(i=1, #d, (-1)^(i+1)*d[i]); }
lista(nmax) = {my(s1 = s(1), s2); for(n = 2, nmax, s2 = s(n); if(s1 == s2, print1(n-1, ", ")); s1=s2); }
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Feb 26 2024
STATUS
approved