OFFSET
0,2
FORMULA
a(n) = [nr] + [nr+r], where r=(1+sqrt(5))/2 and [ ]=floor.
MATHEMATICA
PROG
(Python)
from math import isqrt
def A191402(n): return (n+isqrt(m:=5*n**2)>>1)+(n+1+isqrt(m+10*n+5)>>1) # Chai Wah Wu, Aug 10 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Jun 01 2011
STATUS
approved