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A198778 Primes from merging of 4 successive digits in decimal expansion of Euler-Mascheroni constant A001620.

%I A198778 #17 May 07 2019 14:16:22
%S A198778 577,421,3359,3593,5939,9923,8677,2677,6709,6947,6329,2917,4951,1447,
%T A198778 401,4283,2417,6449,5003,3733,3767,7673,9491,2039,853,5323,6211,4793,
%U A198778 7937,857,7057,29,3547,6043,587,6733,7331,3313,1399,7541,5413,4139,8423,4877,503,8431,3109,1093,9973,3613,8893,8933,17,7247
%N A198778 Primes from merging of 4 successive digits in decimal expansion of Euler-Mascheroni constant A001620.
%C A198778 In contrast to A104938, leading zeros are allowed here, which explains the terms having fewer than 4 digits; e.g., a(32)=29 comes from consecutive digits "...0029..." starting at the 268th decimal digit of gamma (if the initial "0." counts as the first digit). - _M. F. Hasler_, Oct 31 2011
%e A198778 The first four decimal digits of gamma = 0.5772... form the prime 577=a(1).
%p A198778 Digits := 420 ;
%p A198778 for sh from 3 do
%p A198778         p := floor(gamma*10^sh) mod 10000 ;
%p A198778         if isprime(p) then
%p A198778                 printf("%d,",p);
%p A198778         end if;
%p A198778 end do: # _R. J. Mathar_, Oct 31 2011
%t A198778 (* see A104938 for Mmca code *)
%t A198778 Join[{577},Select[FromDigits/@Partition[RealDigits[EulerGamma,10,1000][[1]],4,1],PrimeQ]] (* _Harvey P. Dale_, May 07 2019 *)
%o A198778 (PARI) L=10^4;for(i=3,999,isprime(p=Euler\.1^i%L)&print1(p",")) \\ _M. F. Hasler_, Oct 31 2011
%Y A198778 Cf. A103773, A103789, A103793, A103808-A103812, A104824-A104826, A104843-A104850, A198161-A198177, A198776-A198784.
%K A198778 nonn,base
%O A198778 1,1
%A A198778 _Harvey P. Dale_, Oct 29 2011