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Numbers m such that m + k# is a prime, where k = floor(sqrt(m)) and k# is the primorial A034386(k).
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%I #17 Jan 16 2023 08:10:52

%S 1,2,5,11,13,17,23,29,31,37,41,43,53,59,61,67,71,73,83,97,101,103,107,

%T 127,131,137,149,157,163,167,173,181,193,211,223,229,239,241,263,277,

%U 283,293,307,313,317,337,373,383,389,409,421,449,457,463,479,523,541

%N Numbers m such that m + k# is a prime, where k = floor(sqrt(m)) and k# is the primorial A034386(k).

%C Since every composite number m is divisible by a prime p <= sqrt(m), the sequence contains only noncomposite numbers.

%H <a href="/index/Di#divseq">Index to divisibility sequences</a>

%H <a href="/index/Pri#prime_indices">Index entries for sequences computed from indices in prime factorization</a>

%o (PARI) v=0; for(n=1, 541, pp=primepi(sqrtint(n)); if(pp>v, v=pp); if(isprime(n+factorback(primes(v))), print1(n, ", ")));

%Y Cf. A034386.

%K nonn

%O 1,2

%A _Arkadiusz Wesolowski_, May 24 2018