A292763 Numbers m such that sigma(m)+phi(m) == 2 mod 4.

1, 3, 5, 6, 7, 10, 11, 13, 14, 17, 19, 20, 22, 23, 26, 27, 29, 31, 34, 37, 38, 40, 41, 43, 45, 46, 47, 52, 53, 54, 58, 59, 61, 62, 67, 68, 71, 73, 74, 79, 80, 82, 83, 86, 89, 90, 94, 97, 101, 103, 104, 106, 107, 109, 113, 116, 117, 118, 122, 127, 131, 134, 136, 137, 139, 142, 146, 148, 149, 151, 153, 157

Offset

1,2

Comments

Union of {1}, A191217 and A292762.

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..5000

N. J. A. Sloane, Three (No, 8) Lovely Problems from the OEIS, Experimental Mathematics Seminar, Rutgers University, Oct 05 2017, Part I, Part 2, Slides. (Mentions this sequence)

Mathematica

Do[If[Mod[DivisorSigma[1, n] + EulerPhi[n], 4]==2, Print[n]], {n, 1, 10^3}] (* Vincenzo Librandi, Oct 02 2017 *)

Prog

(PARI) isok(m) = ((sigma(m)+eulerphi(m)) % 4) == 2; \\ Michel Marcus, Oct 02 2017

Crossrefs

Cf. A000010, A000203.

Cf. A191217, A292762.

A065091 (odd primes) is a subsequence. - Michel Marcus, Oct 02 2017

Sequence in context: A182851 A281995 A304452 * A176175 A381241 A157201

Adjacent sequences: A292760 A292761 A292762 * A292764 A292765 A292766

Keyword

nonn

Author

N. J. A. Sloane, Sep 26 2017

Status

approved