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A137599
Numbers n such that sigma(n)=reversal(n)-1.
1
7142167, 75018277, 71859221859
OFFSET
1,1
COMMENTS
a(4) > 10^12. - Giovanni Resta, Oct 28 2012
EXAMPLE
sigma(75018277)=77281056=77281057-1=reversal(75018277)-1, so 75018277 is in the sequence.
MATHEMATICA
Do[If[DivisorSigma[1, n]==FromDigits@Reverse@IntegerDigits@n-1, Print[n]], {n, 1553000000}]
CROSSREFS
Cf. A137598.
Sequence in context: A263069 A034636 A178214 * A151937 A204308 A288481
KEYWORD
base,more,nonn,bref
AUTHOR
Farideh Firoozbakht, Feb 23 2008
EXTENSIONS
a(3) from Giovanni Resta, Oct 28 2012
STATUS
approved