OFFSET
1,1
COMMENTS
Conjecture: sequence of numbers A246456(a(n)): 12, 24, 48, 168, 2160, 17280, 54720, 77280, 221184, 202176, 185328, 249984, 312480, 599040, 725760, 967680, 864864, 1327104, 1489488, 2048256, 1958400, 2439360, 3110400, 3902976, 4852224, 4713984, … is sequence of any multiples of 12.
MATHEMATICA
SequencePosition[Table[DivisorSigma[1, n+DivisorSigma[1, n]], {n, 3344000}], {x_, x_}][[All, 1]] (* The program takes a long time to run. To generate fewer terms but more quickly, reduce the "n" constant. *) (* Harvey P. Dale, Mar 07 2022 *)
PROG
(Magma) [n:n in[1..1000000] | SumOfDivisors(n+SumOfDivisors(n)) eq SumOfDivisors(n+1+SumOfDivisors(n+1))]
(PARI)
for(n=1, 10^7, if(sigma(n+sigma(n))==sigma(n+1+sigma(n+1)), print1(n, ", "))) \\ Derek Orr, Sep 07 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Sep 07 2014
EXTENSIONS
More terms from Derek Orr, Sep 07 2014
STATUS
approved