A191001 - OEIS

%I #20 May 15 2020 04:38:05

%S 1,2,4,5,9,10,18,26,34,38,45,50,57,88,108,115,161,208,224,225,238,240,

%T 264,354,597,634,984,1008,1080,1468

%N Indices k where A191620(k) = A191751(k).

%F {k: A191620(k)=A191751(k)}.

%e 1 is a term because A191620(1) = A191751(1) = 0;

%e 2 is a term because A191620(2) = A191751(2) = 1.

%p A191751 := proc(n) local k; for k from 0 do if isprime((2^n-1)*2^n-k) then return k: end if : end do: end proc:

%p A191620 := proc(n) local k: for k from 0 do if isprime((2^n-k)*2^n-1) then return k: end if: end do: end proc:

%p for n from 1 do if A191751(n) = A191620(n) then printf("%d,\n",n); end if; end do: # _R. J. Mathar_, Jun 25 2011

%Y Cf. A191620, A191751.

%K nonn,less,more

%O 1,2

%A _Juri-Stepan Gerasimov_, Jun 15 2011

%E a(25)-a(30) from _Jinyuan Wang_, May 15 2020