A074311 a(1) = 1; a(2) = 2; a(n) = smallest number greater than the previous term such that the average of three successive terms is a prime.
1, 2, 3, 4, 8, 9, 16, 26, 27, 34, 50, 57, 70, 74, 75, 88, 104, 111, 112, 116, 153, 178, 188, 207, 238, 242, 243, 268, 278, 285, 286, 308, 327, 358, 362, 381, 394, 416, 417, 424, 452, 453, 466, 470, 501, 502, 506, 519, 538, 566, 567, 574, 590, 597, 610, 614, 615
Offset: 1
Keywords
Examples
a(5) = 8 because 1/3(a(3) + a(4) + a(5)) is a prime.
Links
- Harvey P. Dale, Table of n, a(n) for n = 1..1000
Programs
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Mathematica
sngpt[{a_,b_}]:=Module[{k=b+1},While[CompositeQ[Mean[{a,b,k}]],k++];{b,k}]; NestList[sngpt,{1,2},60][[All,1]] (* Harvey P. Dale, May 29 2019 *)
Comments