A018124 - OEIS

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

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OFFSET

0,3

LINKS

Table of n, a(n) for n=0..41.

PROG

(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

CROSSREFS

Cf. A005533.

Sequence in context: A369571 A274200 A018052 * A133034 A124745 A000931

Adjacent sequences: A018121 A018122 A018123 * A018125 A018126 A018127

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

STATUS

approved