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A376750 Indices n where a run of primes begins in A376198.

%I A376750 #19 Oct 07 2024 14:17:37
%S A376750 2,9,23,52,110,231,472,965,1958,3962,7980,16029,32181,64597,129574,
%T A376750 259798,520835,1043833,2091473,4190135,8392863,16809322,33661860,
%U A376750 67402676,134952624,270177158,540861852,1082667610,2167106199,4337519113,8681255531,17374202846,34770433922,69582458821,139243546013,278635987083
%N A376750 Indices n where a run of primes begins in A376198.
%o A376750 (Python)
%o A376750 from itertools import count, islice
%o A376750 from sympy import isprime, nextprime
%o A376750 def A376750_4gen(): # generator of terms for A376750..4
%o A376750     an, smc, smp = 2, 4, 3,
%o A376750     wasprime = startp = startn = endp = endn = rl = 0
%o A376750     for n in count(2):
%o A376750         if not isprime(an):
%o A376750             if wasprime: # a run has ended
%o A376750                 endn, endp = n-1, wasprime
%o A376750                 yield startn, startp, endn, endp, rl
%o A376750             an = smp if an == 2*smp else smc
%o A376750             wasprime = 0 # False
%o A376750         else:
%o A376750             if not wasprime: # a run has started
%o A376750                 startn, startp, rl = n, an, 1
%o A376750             else: rl += 1
%o A376750             wasprime = an
%o A376750             an = smp if smp < smc else smc
%o A376750         if an == smp: smp = nextprime(smp)
%o A376750         else:
%o A376750             smc += 1
%o A376750             while isprime(smc): smc += 1
%o A376750 print([out[0] for out in list(islice(A376750_4gen(), 15))]) # _Michael S. Branicky_, Oct 03 2024
%Y A376750 Cf. A376198-A376201, A376751-A376754.
%K A376750 nonn
%O A376750 1,1
%A A376750 _N. J. A. Sloane_, Oct 03 2024
%E A376750 a(14)-a(33) from _Michael S. Branicky_, Oct 04 2024
%E A376750 a(34)-a(36) from _Michael S. Branicky_, Oct 07 2024