login
A187712
Composite numbers k such that k = (product of divisors of k) mod (sum of divisors of k).
1
10, 20, 33, 40, 76, 136, 145, 207, 261, 385, 464, 528, 588, 897, 931, 1441, 1519, 1611, 1816, 1989, 2016, 2205, 2241, 2353, 3280, 3504, 3724, 3808, 4067, 4320, 4864, 5696, 6256, 7201, 7345, 8036, 10688, 10936, 11376, 13000, 16840, 17101, 18625, 19359, 19504, 19840
OFFSET
1,1
LINKS
FORMULA
A187711 INTERSECT A002808.
MATHEMATICA
Select[Range[20000], CompositeQ[#] && PowerMod[#, DivisorSigma[0, #]/2, DivisorSigma[1, #]] == # &] (* Amiram Eldar, Mar 22 2024 *)
PROG
(PARI) is1(n) = my(f = factor(n), s = sigma(f), d = numdiv(f)); if(d%2, Mod(sqrtint(n), s)^d, Mod(n, s)^(d/2)) == n;
is(n) = n > 1 && !isprime(n) && is1(n); \\ Amiram Eldar, Mar 22 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
More terms from Amiram Eldar, Mar 22 2024
STATUS
approved