A191404 a(n) = A000201(n) + A000201(n+3).

4, 7, 11, 13, 17, 20, 23, 27, 29, 33, 37, 39, 43, 46, 49, 53, 55, 59, 62, 65, 69, 71, 75, 79, 81, 85, 88, 91, 95, 97, 101, 105, 107, 111, 114, 117, 121, 123, 127, 130, 133, 137, 139, 143, 147, 149, 153, 156, 159, 163, 165, 169, 172, 175, 179, 181, 185, 189, 191, 195, 198, 201, 205, 207, 211, 215, 217, 221, 224, 227

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 A191404(n): return (n+isqrt(m:=5*n**2)>>1)+(n+3+isqrt(m+30*n+45)>>1) # Chai Wah Wu, Aug 10 2022

Crossrefs

Cf. A000201, A191402.

Sequence in context: A310720 A310721 A091855 * A288374 A308199 A310722

Adjacent sequences: A191401 A191402 A191403 * A191405 A191406 A191407

Keyword

nonn

Author

Clark Kimberling, Jun 01 2011

Status

approved