A227179 After initial 0, integers from 0 to n(n-1) followed by integers from 0 to n(n+1) and so on.

0, 0, 0, 1, 2, 0, 1, 2, 3, 4, 5, 6, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30

Offset: 0

Author

Antti Karttunen, Jul 03 2013

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 0..9951

Crossrefs

Cf. A002378, A006527, A227177, A227181, A227182.

Programs

Mathematica

Flatten[(Range[(#-2) (#-1)+1]-1&)[Range[7]]] (* Peter J. C. Moses, Jul 11 2013 *)

Python

from sympy import integer_nthroot
def A227179(n): return n-1-(f:=lambda x:x*(x**2+2))((m:=integer_nthroot(k:=3*n,3)[0])-(k<=f(m)))//3 # Chai Wah Wu, Nov 07 2024

Scheme

(define (A227179 n) (- n (+ 1 (A006527 (- (A227177 n) 1)))))

Formula

a(n) = n - (1 + A006527(A227177(n)-1)).