A083248 Numbers k such that A045763(k) > A000010(k) > A000005(k).

36, 40, 42, 48, 50, 54, 56, 60, 66, 70, 72, 78, 80, 84, 88, 90, 96, 98, 100, 102, 104, 105, 108, 110, 112, 114, 120, 126, 130, 132, 136, 138, 140, 144, 150, 152, 154, 156, 160, 162, 168, 170, 174, 176, 180, 182, 184, 186, 190, 192, 196, 198, 200, 204, 208, 210

Offset

1,1

Comments

Primes are not terms since A045763(p) = 0 < A000005(p) = 2 for a prime p.

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Example

k = 100 is a term since d(k) = 9, phi(k) = 40, unrelateds(k) = 100 - 9 - 40 + 1 = 52, and 52 > 40 > 9 holds.

Mathematica

Do[r=EulerPhi[n]; d=DivisorSigma[0, n]; u=n-r-d+1; If[Greater[u, r]&&Greater[r, d], Print[n, {d, r, u}]], {n, 1, 1000}]

Prog

(PARI) isok(k) = {my(f = factor(k), d = numdiv(f), r = eulerphi(f), u = k - r - d + 1); u > r && r > d; } \\ Amiram Eldar, Feb 08 2025

Crossrefs

Cf. A000005, A000010, A045763, A073757, A083243, A083244, A083245, A083246, A083247, A020488.

Sequence in context: A248372 A349705 A129288 * A360765 A077090 A254836

Adjacent sequences: A083245 A083246 A083247 * A083249 A083250 A083251

Keyword

nonn,changed

Author

Labos Elemer, May 07 2003

Status

approved