A253776 - OEIS

%I #13 Sep 18 2024 02:51:25

%S 13,71,137,251,353,523,1013,1033,2213,4933,24421,32803,39341,59063,

%T 78137,117701,125053,140663,148933,205441,274693,279949,343073,371311,

%U 456613,493121,524309,571873,681563,912773,1225153,1594339,1953253,2406241,2924353,3241943,3652421

%N Primes representable as x^y + x + y, where x>1, y>1 are integers.

%H Robert Israel and Charles R Greathouse IV, <a href="/A253776/b253776.txt">Table of n, a(n) for n = 1..10000</a> (first 800 terms from Israel)

%p N:= 10^6; # to get all terms <= N

%p A:= select(t -> t <= N and isprime(t), {seq(seq(x^y+x+y, y = 2..floor(log[x](N-x))), x=2..floor(sqrt(N)))}, N):

%p sort(convert(A,list)); # _Robert Israel_, Sep 18 2024

%o (PARI) list(lim)=my(v=List()); forstep(y=3,oo,2, if(2^y+y+2>lim, break); for(x=2,oo, my(p=x^y+x+y); if(p>lim, break); if(isprime(p), listput(v,p)))); Set(v) \\ _Charles R Greathouse IV_, Sep 18 2024

%Y Cf. A253775, A253777.

%K nonn

%O 1,1

%A _Alex Ratushnyak_, Jan 12 2015