Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #36 Oct 16 2024 16:10:44
%S 1,65539,393225,1769499,7077969,26542323,95552217,334432395,
%T 1146624417,1722371299,14608041,1766175739,1875647473,1800754131,
%U 366148473,1022489195,692115265,1392739779,2127401289,229749723,1559239569,845238963,1775695897,899541067,153401569
%N Consecutive internal states of the linear congruential pseudo-random number generator RANDU that was used in the IBM Scientific Subroutine Library for IBM System/360 computers in the 1970's.
%C Due to a poor choice of the multiplier the generator fails most 3-d criteria for randomness. 9*a(n-2)-6*a(n-1)+a(n) = 0 mod 2^31. This was first described by George Marsaglia. The animated gif in the link demonstrates the deficient behavior. The animation shows 10000 points, each of whose coordinate triples (x,y,z) were formed from successive outputs of the generator. From a suitable view angle, it can be seen that these points do not fill the 3-D space, but lie in a few planes parallel to each other.
%D D. E. Knuth, The Art of Computer Programming Third Edition. Vol. 2 Seminumerical Algorithms. Chapter 3.3.4 The Spectral Test, Page 107. Addison-Wesley 1997.
%H Alois P. Heinz, <a href="/A096555/b096555.txt">Table of n, a(n) for n = 1..10000</a>
%H Sarah Belet, <a href="https://web.archive.org/web/20170207170457/http://www.aums.org.au/talks/s_belet/SarahB_Round_the_Twist.pdf">'Round the Twist</a>, Blog Entry, Friday May 16 2014
%H George Marsaglia, <a href="https://doi.org/10.1073/pnas.61.1.25">Random numbers fall mainly in the planes</a>, Proceedings of the National Academy of Sciences, 61, 25-28, 1968.
%H Hugo Pfoertner, <a href="/A096555/a096555.gif">Animation showing the deficient 3-d behavior</a>, 2024.
%H <a href="/index/Ps#PRN">Index entries for sequences related to pseudo-random numbers.</a>
%H <a href="/index/Rec#order_536870912">Index entries for linear recurrences with constant coefficients</a>, order 536870912.
%F a(1)=1, a(n) = 65539*a(n-1) mod 2^31. The sequence is periodic with period length 2^29.
%p a:= proc(n) option remember; `if`(n<2, n,
%p irem(65539 *a(n-1), 2147483648))
%p end:
%p seq(a(n), n=1..30); # _Alois P. Heinz_, Jun 10 2014
%t NestList[Mod[#*65539, 2^31] &, 1, 50] (* _Paolo Xausa_, Aug 29 2024 *)
%o (PARI) a(n)=lift(Mod(65539,2^31)^(n-1)) \\ _Charles R Greathouse IV_, Jan 13 2016
%Y Cf. A096550-A096561 for other pseudo-random number generators.
%K nonn,easy
%O 1,2
%A _Hugo Pfoertner_, Jul 19 2004