OFFSET
1,1
COMMENTS
EXAMPLE
14 is a term because Product_{d|14} sigma(d) = 1 * 3 * 8 * 24 = Product_{d|15} sigma(d) = 1 * 4 * 6 * 24 = 576.
MATHEMATICA
Select[Range[5000], Times @@ DivisorSigma[1, Divisors[#]] == Times @@ DivisorSigma[1, Divisors[# + 1]] &] (* G. C. Greubel, Dec 26 2016 *)
PROG
(Magma) [n: n in [1..1000] | &*[SumOfDivisors(d): d in Divisors(n)] eq &*[SumOfDivisors(d): d in Divisors(n+1)]]
(PARI) isok(n) = my(d = divisors(n), dd = divisors(n+1)); prod(k=1, #d, sigma(d[k])) == prod(k=1, #dd, sigma(dd[k])); \\ Michel Marcus, Dec 26 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Dec 25 2016
EXTENSIONS
More terms from Michel Marcus, Dec 26 2016
STATUS
approved