A071846 phi(n) + phi(reverse(n)) = sigma(n).

3, 26, 221, 635, 1702, 4945, 5038, 26596, 27927, 62783, 195723, 210221, 364287, 489955, 495995, 525833, 901303, 909503, 2747761, 2750247, 2941119, 3926146, 4463651, 4484831, 4630475, 4769947, 5531305, 6099313, 6482845, 6917881

Offset

1,1

Links

Table of n, a(n) for n=1..30.

Example

phi(221) + phi(reverse(221)) = phi(221) + phi(122) = 192 + 60 = 252 = sigma(221).

Mathematica

r = {}; Do[ If[ EulerPhi[n] + EulerPhi[ FromDigits[ Reverse[ IntegerDigits[n]]]] == DivisorSigma[1, n], r = Append[r, n]], {n, 1, 10^7}]; r
Select[Range[7*10^6], EulerPhi[#]+EulerPhi[IntegerReverse[#]] == DivisorSigma[ 1, #]&] (* Harvey P. Dale, Aug 26 2021 *)

Crossrefs

Sequence in context: A037790 A037671 A037797 * A357036 A067858 A052141

Adjacent sequences: A071843 A071844 A071845 * A071847 A071848 A071849

Keyword

base,nonn

Author

Joseph L. Pe, Jun 09 2002

Extensions

Edited and extended by Robert G. Wilson v, Jun 11 2002

Corrected by Harvey P. Dale, Aug 26 2021

Status

approved