[seqfan] Re: A159580 easy, more

William Rex Marshall w.r.marshall at actrix.co.nz
Sun Oct 2 02:05:44 CEST 2011

On 2/10/2011 8:58 a.m., N. J. A. Sloane wrote:
> Concerning A159577 and the associated sequences A159578 ... A159580 ...:
> As Sean observed, the terms do not match the definiton.
> The definition produces A116536, with related sequences A051838 and A196415.
> But A159577 contains a UBASIC program. Can someone who understands
> BASIC please read that program and explain what it does?
> Then we can change the definition of A159577 etc to match
> the values of the terms.
> Neil
> _______________________________________________
> Seqfan Mailing list - http://list.seqfan.eu/

UBASIC can be run in Windows 7 under DOSBox.

The word "stop" in the program should be changed to "pause", otherwise 
the program halts prematurely. Running the program then generates output 
like that shown in the screenshot at 
http://users.actrix.co.nz/w.r.marshall/temporary/a159577.gif . The 
sequence terms are the third terms in alternate rows after the first in 
the program output, when those terms are integral.

The program is buggy as it is including odd prime squares > 9 (i.e. 25, 
49, 121, 169, 289, 361, 529 ...) along with the primes in its 
calculations, resulting in the third term being 
(2*3*5*7*11*13*17*19*23*25) / (2+3+5+7+11+13+17+19+23+25) = 44618574.

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