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A191404
a(n) = A000201(n) + A000201(n+3).
2
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.
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
Sequence in context: A310720 A310721 A091855 * A288374 A308199 A310722
KEYWORD
nonn
AUTHOR
Clark Kimberling, Jun 01 2011
STATUS
approved