A191403 a(n) = A000201(n) + A000201(n+2).

3, 5, 9, 12, 15, 19, 21, 25, 28, 31, 35, 38, 41, 45, 47, 51, 54, 57, 61, 63, 67, 70, 73, 77, 80, 83, 87, 89, 93, 96, 99, 103, 106, 109, 113, 115, 119, 122, 125, 129, 131, 135, 138, 141, 145, 148, 151, 155, 157, 161, 164, 167, 171, 173, 177, 180, 183, 187, 190, 193, 197, 199, 203, 206, 209, 213, 216, 219, 223, 225

Offset

0,1

Comments

See A191402.

Links

Table of n, a(n) for n=0..69.

Mathematica

(See A191402.)

Prog

(Python)
from math import isqrt
def A191403(n): return (n+isqrt(m:=5*n**2)>>1)+(n+isqrt(m+(5*(n+1)<<2))>>1)+1 # Chai Wah Wu, Aug 10 2022

Crossrefs

Cf. A000201, A191402.

Sequence in context: A304525 A310039 A091785 * A233779 A287105 A003075

Adjacent sequences: A191400 A191401 A191402 * A191404 A191405 A191406

Keyword

nonn

Author

Clark Kimberling, Jun 01 2011

Status

approved