OFFSET
1,5
FORMULA
G.f.: x^2*y/((1 - x)*(1 - x*y)^2). - Stefano Spezia, Feb 21 2024
EXAMPLE
Triangle begins:
0;
1, 0;
1, 2, 0;
1, 2, 3, 0;
1, 2, 3, 4, 0;
...
MATHEMATICA
Flatten[Table[Mod[k, n], {n, 15}, {k, n}]] (* Harvey P. Dale, Mar 21 2012 *)
PROG
(Python)
from math import isqrt, comb
def A048151(n): return n-comb((m:=isqrt(k:=n+1<<1))+(k>m*(m+1)), 2) # Chai Wah Wu, Apr 09 2025
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
STATUS
approved
