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%I #24 Jan 02 2023 12:30:49
%S 1,2,3,15,39,2119,4189897,5812974437
%N Indices k such that prime(k) - k is a power of 2.
%C The only primes in this sequence below primepi(10^8) are 2, 3 and 4189897.
%C prime(5812974437) - 5812974437 = 2^37. - _Giovanni Resta_, Apr 10 2013
%C a(9) > 1.4*10^16, if it exists. - _Chai Wah Wu_, Apr 24 2018
%H <a href="http://list.seqfan.eu/oldermail/seqfan/2013-April/011029.html">Re: 2^k - prime(p) or prime(p) - 2^k ?</a>, SeqFan mailing list, Apr 10 2013
%F A000040(a(n))-a(n) = 2^floor(log[2](A000040(a(n)))) for all n>1.
%o (PARI) n=0;forprime(p=1,10^8,n++;(t=p-n)==1<<valuation(t,2)&print1(n","))
%Y Cf. A014689.
%K nonn,more
%O 1,2
%A _M. F. Hasler_, Apr 10 2013
%E a(8) from _Giovanni Resta_, Apr 10 2013
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