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The first nonprimes after the primes.
3

%I #14 Aug 07 2024 03:18:55

%S 4,4,6,8,12,14,18,20,24,30,32,38,42,44,48,54,60,62,68,72,74,80,84,90,

%T 98,102,104,108,110,114,128,132,138,140,150,152,158,164,168,174,180,

%U 182,192,194,198,200,212,224,228,230,234,240,242,252,258,264,270,272

%N The first nonprimes after the primes.

%C Essentially the same as A135731, A055670, A028815 and A008864. [_R. J. Mathar_, Mar 13 2010]

%H G. C. Greubel, <a href="/A175216/b175216.txt">Table of n, a(n) for n = 1..10000</a>

%F a(1) = 4, for n >= 2, a(n) = A008864(n) = A000040(n) + 1.

%t Table[Prime[n] +1 +Boole[n==1], {n,100}] (* _G. C. Greubel_, Aug 06 2024 *)

%o (Magma) [n eq 1 select 4 else NthPrime(n) +1: n in [1..100]]; // _G. C. Greubel_, Aug 06 2024

%o (SageMath)

%o def A175216(n): return nth_prime(n) +1 +int(n==1)

%o [A175216(n) for n in range(1,101)] # _G. C. Greubel_, Aug 06 2024

%Y Cf. A000040, A008864, A028815, A055670, A135731.

%K nonn,easy

%O 1,1

%A _Jaroslav Krizek_, Mar 06 2010