A196936 - OEIS

%I #10 Apr 03 2023 10:36:12

%S 5,7,10,15,17,20,26,32,33,35,49,62,54,63,64,74,69,71,91,98,92,102,109,

%T 116,120,124,152,137,147,144,140,171,165,192,197,195,199,201,200,218,

%U 220,250,238,229,239,230,236,277,267,281,300,299,301,314,312,332,325

%N a(n) is the first occurrence of n in sequence A196935.

%C The Mathematica program gives the first 57 terms.

%H Definition of <a href="https://t5k.org/top20/page.php?id=14">Arithmetic Progressions of Primes</a>

%e A196935(5) = 1, so a(1) = 5; (consider the offset of 5 for A196935)

%e A196935(7) = 2, and all A196935(k) <> 2 for k < 7, so a(2) = 7

%t max = 57; Array[fa, max]; Do[fa[i] = 0, {i, 1, max}]; i = 4; done = 0; While[done < max, i++; p = Prime[i]; j = 0; ct = 0; While[j++; df = 6*j; df < p, If[(PrimeQ[p + df]) && (PrimeQ[p - df]), ct++]]; If[ct <= max, If[fa[ct] == 0, fa[ct] = i; done++]]]; Table[fa[i], {i, 1, max}]

%Y Cf. A196935, A196934.

%K nonn

%O 1,1

%A _Lei Zhou_, Oct 07 2011