A081849 Consider recurrence b(0) = (2n+1)/2, b(n) = b(0)*ceiling(b(n-1)); sequence gives first integer reached.

3, 20, 14, 468, 33, 299, 60, 47328, 95, 1218, 138, 25475, 189, 3161, 248, 20830128, 315, 6512, 390, 181138, 473, 11655, 564, 9015167, 663, 18974, 770, 671745, 885, 28853, 1008, 38906570560, 1139, 41676, 1278, 1799888, 1425, 57827, 1580, 110341278, 1743, 77690

Offset

1,1

Links

Table of n, a(n) for n=1..42.

Maple

Digits := 100: c := ceil; A081849 := proc(a) local i, t0, t; t0 := a; t := 0; for i from 1 to 100 do if whattype(t0) <> integer then t0 := a*c(t0); t := t+1; else RETURN(t0); fi; od; RETURN('FAIL'); end;

Prog

(Python)
from math import ceil
from fractions import Fraction
def a(n):
  b0 = b = Fraction((2*n+1), 2)
  while b.denominator != 1: b = b0*ceil(b)
  return b.numerator
print([a(n) for n in range(1, 43)]) # Michael S. Branicky, Mar 20 2021

Crossrefs

A001511 gives number of steps to reach an integer. Cf. A073524, A074078.

Sequence in context: A126810 A115280 A212995 * A333667 A169642 A222482

Adjacent sequences: A081846 A081847 A081848 * A081850 A081851 A081852

Keyword

nonn

Author

N. J. A. Sloane, Apr 13 2003

Status

approved