[seqfan] Re: A112775: consecutive terms with common gap 1.

[Zak Seidov]

Smallest n such that  
  n...n+13 are terms in A112775
is 37065885.


>Четверг,  9 февраля 2017, 7:34 +03:00 от Charles Greathouse <charles.greathouse at case.edu>:
>
>Here's a crude one-line (on a sufficiently wide monitor) sieve:
>
>semisearch(a,b,sz=12,m=Mod(1,6))=my(v=List(),t,gap=m.mod*sz);
>forprime(p=2,sqrtint(b\1+1)-1,forprime(q=max(p,(a-1)\p+1),b\p, t=p*q;
>if(t==m, listput(v,p*q)))); v=Set(v); for(i=sz+1,#v,
>if(v[i]-v[i-sz]==gap,return(v[i-sz])))
>
>which can be invoked like so:
>
>forstep(n=1,1e12,10^6, t=semisearch(n,n+10^6+100,11,Mod(1,6)); if(t,
>return(t\6))) \\ rediscovers 10083 in 140 ms
>forstep(n=1,1e12,10^6, t=semisearch(n,n+10^6+100,12,Mod(1,6)); if(t,
>return(t\6)))
>forstep(n=1,1e12,10^6, t=semisearch(n,n+10^6+100,14,Mod(5,6)); if(t,
>return(t\6)))
>forstep(n=1,1e12,10^6, t=semisearch(n,n+10^6+100,13,Mod(1,6)); if(t,
>return(t\6)))
>
>Charles Greathouse
>Case Western Reserve University
>
>On Wed, Feb 8, 2017 at 8:43 PM, Zak Seidov < zakseidov at mail.ru > wrote:
>
>>
>>  For n=10083 and 214983,
>> n through n+11 are terms in A112775 (Numbers n such that 6n+1 is
>> semiprime).
>> Are there longer sets of consecutive terms with common gap 1 in  A112775?
>>
>> Zak  Seidov
>> PS The same Q for A112776  ( Numbers n such that 6n+5 is semiprime).
>>
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>>
>
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