A054351 Successive generations of the Kolakoski sequence A000002.

1, 12, 1221, 1221121, 12211212212, 122112122122112112, 1221121221221121122121121221, 1221121221221121122121121221121121221221121, 12211212212211211221211212211211212212211212212112112212211212212

Offset: 0

Author

N. J. A. Sloane, May 07 2000

Keywords

• nonn
• easy

Crossrefs

Cf. A054348, A054349, A054350, A054352, A042942, A000002.

Word lengths give A054352.

Programs

Python

from itertools import accumulate, groupby, repeat
def K(n, _):
  c, s = "12", ""
  for i, k in enumerate(str(n)): s += c[i%2]*int(k)
  return int(s + c[(i+1)%2])
def aupton(nn): return list(accumulate(repeat(1, nn+1), K))
print(aupton(8)) # Michael S. Branicky, Jan 12 2021

Extensions

More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 05 2003