A018124 Powers of fifth root of 4 rounded to nearest integer.

1, 1, 2, 2, 3, 4, 5, 7, 9, 12, 16, 21, 28, 37, 49, 64, 84, 111, 147, 194, 256, 338, 446, 588, 776, 1024, 1351, 1783, 2353, 3104, 4096, 5405, 7132, 9410, 12417, 16384, 21619, 28526, 37641, 49667, 65536, 86475

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn

Crossrefs

Cf. A005533.

Programs

Python

from gmpy2 import iroot_rem
def A018124(n):
    i, j = iroot_rem(1<<(n<<1),5)
    return int(i)+int(j<<5>=10*i*((i*((i*(i+1)<<1)+1)<<2)+1)+1) # Chai Wah Wu, Jun 20 2024