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A117129 Primes not occurring as |differences| in Cald's sequence A006509.

%I A117129 #25 Mar 11 2024 04:53:50
%S A117129 641,1213,2617,2957,3727,5443,9283,17359,33829,66173,131303,264763,
%T A117129 494743,957547,1888157,3753647,7490797,14961157,29899357,59773871,
%U A117129 119551489,239106347,478234723,956607929,1913366111,3826828409,7653840367,15308666783,30619196381,57415599151
%N A117129 Primes not occurring as |differences| in Cald's sequence A006509.
%C A117129 In other words, primes that do not occur as absolute values of differences of successive terms in Cald's sequence A006509.
%F A117129 a(n) = prime(A112877(n) - 1).
%o A117129 (Python)
%o A117129 from itertools import count, islice
%o A117129 from sympy import nextprime
%o A117129 def A117129_gen(): # generator of terms
%o A117129     a, aset, p = 1, {1}, 2
%o A117129     for c in count(2):
%o A117129         if (b:=a-p) > 0 and b not in aset:
%o A117129             a = b
%o A117129         elif (b:=a+p) not in aset:
%o A117129             a = b
%o A117129         else:
%o A117129             a = 0
%o A117129             yield p
%o A117129         aset.add(a)
%o A117129         p = nextprime(p)
%o A117129 A117129_list =  list(islice(A117129_gen(),10)) # _Chai Wah Wu_, Mar 04 2024
%Y A117129 Cf. A006509, A112877.
%K A117129 nonn
%O A117129 1,1
%A A117129 _N. J. A. Sloane_, Apr 20 2006
%E A117129 a(19)-a(26) from _Donovan Johnson_, Feb 18 2010
%E A117129 a(27)-a(29) from _Chai Wah Wu_, Mar 04 2024
%E A117129 a(30) from _Chai Wah Wu_, Mar 10 2024