A116031 sigma(n)-phi(n) and sigma(n)+phi(n) are two palindromes greater than 2.

4, 388, 403, 10010, 11481, 12215, 41242, 42173, 44243, 223261, 223487, 403303, 2302031, 3288877, 3490447, 32605627, 40077553, 40162802, 42311323, 44044043, 117426509, 222613051, 230777581, 232075811, 287772226, 307222207, 327067459

Offset

1,1

Links

Table of n, a(n) for n=1..27.

Example

sigma(3288877)-phi(3288877) = 44444 and
sigma(3288877)+phi(3288877)=6577756.

Crossrefs

Cf. A115897, A116030.

Sequence in context: A006237 A181044 A339449 * A115049 A307929 A202172

Adjacent sequences: A116028 A116029 A116030 * A116032 A116033 A116034

Keyword

nonn,base

Author

Giovanni Resta, Feb 13 2006

Extensions

a(15)-a(27) from Donovan Johnson, Feb 05 2010

Status

approved