User:Jean-Bernard François

$whoami?

I'm Jean-Bernard François (aka infofiltrage) born in France the 03/05/69 & DP Engineer (Engineering Graphics Software).

My current blog is Bondissant (almost art from geometry).

I love number theory, mathematics, and of course OEIS.

I only worked under Debian Linux System with LibreOffice, Inkscape and a LiberKey.

Contributions

A099730 | A000302

Useful Links

• HelpPage
• FAQ

Others

Collatz | Diophantine | Primes | Number Theory

Sequence of the Day

[talk]

Sequence of the Day for April 27

A024816: Antisigma (n):

x̅σ (n) := ∑ n i  = 1 i∤n i = tn  −  σ (n)

, for

n   ≥   1

.

{ 0, 0, 2, 3, 9, 9, 20, 21, 32, 37, ... }

For primes

p

,

x̅σ (  p) = t p  − 1  −  1 = p  (  p  − 1) 2  −  1

, where

t p  − 1

is the

(  p  −  1)

 -th triangular number. Compare with Euler's cototient function

x̅φ (n)

.