A309541 Representable positive integers n that are not the inverse of their inverse in binary64 (double precision) IEEE 754 floating-point arithmetic (Version where 1 and n*(1/n) are unequal).

49, 98, 103, 107, 161, 187, 196, 197, 206, 214, 237, 239, 249, 253, 322, 347, 374, 389, 392, 394, 412, 417, 425, 428, 443, 474, 478, 479, 491, 498, 499, 501, 503, 506, 509, 561, 569, 644, 685, 691, 694, 725, 729, 735, 737, 748, 753, 765, 778, 779, 784, 788, 789, 797, 809, 817, 823, 824, 829, 833, 834, 837, 841, 849, 850

Offset

1,1

Links

Andrey Zabolotskiy, Table of n, a(n) for n = 1..10000

Efstratios Gallopoulos, Scientific Computation I, five terms provided (in Greek) [broken link]

Mark, comment on blog post "Rundungsfehler im Flash Player?", eight terms (in German)

koDoz, comment in thread "Welche Grenzwerte gelten für Zahlen, Strings usw?", nine terms (in German)

Prog

(Python 2 or Python 3)
for i in range(1, 1000):
  if i*(1./i) != 1: print(i)
(Fortran)
      doubleprecision one, r
      integer i
      parameter (one=1.0D0)
      do 10 i = 1, 500
      R = one / dble(i)
      if ( R * dble(i) .ne. one) write (*, 1000) i
1000  format (i0)
10    continue
      end
C Hugo Pfoertner, Jan 18 2024

Crossrefs

See A275419 for the n != 1/(1/n) version.

Sequence in context: A044030 A165339 A131601 * A174386 A044138 A043394

Adjacent sequences: A309538 A309539 A309540 * A309542 A309543 A309544

Keyword

nonn,fini

Author

Adam M. Scherlis, Aug 06 2019

Status

approved