

A136542


Numbers n such that sigma(n)=reversal(n)+5.


0



57, 58, 597, 1642, 5997, 5998, 51718, 160042, 556438, 599997, 5999998, 15810772, 59999997, 59999998, 160000000042
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OFFSET

1,1


COMMENTS

I. If 2*10^m1 is prime then n=3*(2*10^m1) is in the sequence(the proof is easy).
II. If 3*10^m1 is prime then n=2*(3*10^m1) is in the sequence (the proof is easy).
III. If m>1 and 8*10^m+21 is prime then n=2*(8*10^m+21) is in the sequence(the proof is easy).
a(16) > 10^12.  Giovanni Resta, Oct 28 2012


LINKS

Table of n, a(n) for n=1..15.


EXAMPLE

sigma(57)=80=75+5=reversal(57)+5, so 57 is in the sequence.


MATHEMATICA

Do[If[DivisorSigma[1, n]==FromDigits@Reverse@IntegerDigits#n+5, Print[n]], {n, 160000000}]


CROSSREFS

Cf. A069216.
Sequence in context: A291496 A036184 A217923 * A042623 A072466 A216183
Adjacent sequences: A136539 A136540 A136541 * A136543 A136544 A136545


KEYWORD

base,more,nonn


AUTHOR

Farideh Firoozbakht, Jan 08 2008


EXTENSIONS

a(15) from Giovanni Resta, Oct 28 2012


STATUS

approved



