

A235710


Composite numbers n such that sum of the proper divisors of n is a power of 10.


0



14, 124, 194, 1324, 1994, 13324, 133324, 1130324, 1333324, 13333324, 62496048, 133333324, 92782317392
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OFFSET

1,1


COMMENTS

Composite numbers n such that reversal(sigma(n)n))=1.
If n is prime then sum of the proper divisors of n is 10^0.
If m is a natural number and p=10^m3 is prime then 2*p is in the sequence.
If m is a natural number and p=(10^m7)/3 is prime then 4*p is in the sequence.


LINKS



EXAMPLE

sigma(14)14 = 1+2+7 = 10, sigma(124)124 = 1+2+4+31+62 = 100.


MATHEMATICA

r[n_]:=FromDigits[Reverse[IntegerDigits[n]]]; Do[If[!PrimeQ[n]&& r[DivisorSigma[1, n]n]==1, Print[n]], {n, 200000000}]


CROSSREFS



KEYWORD

nonn,base,more


AUTHOR



EXTENSIONS



STATUS

approved



