A230006 Numbers n such that sigma(n) + phi(n) = reversal(n) + 1.

1, 37, 225, 397, 11112722, 1309286244182

Offset

1,2

Comments

If p=4*10^m-3 is prime then p is in the sequence.

a(7) > 10^13. - Giovanni Resta, Feb 08 2014

Links

Table of n, a(n) for n=1..6.

Example

sigma(37)+phi(37)=38+36=73+1=reversal(37)+1.

Mathematica

r[n_] := FromDigits[Reverse[IntegerDigits[n]]]; Do[If[DivisorSigma[1, n] + EulerPhi[n] == r[n]+1, Print[n]], {n, 1000000000}]

Crossrefs

Cf. A000010, A000203, A004086, A230004, A230005.

Sequence in context: A327033 A052166 A142010 * A284987 A133958 A088544

Adjacent sequences: A230003 A230004 A230005 * A230007 A230008 A230009

Keyword

nonn,base,more

Author

Farideh Firoozbakht, Dec 02 2013

Extensions

a(6) from Giovanni Resta, Feb 06 2014

Status

approved