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A229609
Array: each row starts with the least prime not in a previous row, and each prime p in a row is followed by the greatest prime < 3*p.
3
2, 5, 3, 13, 7, 11, 37, 19, 31, 17, 109, 53, 89, 47, 23, 317, 157, 263, 139, 67, 29, 947, 467, 787, 409, 199, 83, 41, 2837, 1399, 2357, 1223, 593, 241, 113, 43, 8501, 4177, 7069, 3659, 1777, 719, 337, 127, 59, 25471, 12527, 21193, 10973, 5323, 2153, 1009
OFFSET
1,1
COMMENTS
Conjectures: (row 1) = A126031, (column 1) = A164952, and for each row r(k), the limit of r(k)/3^k exists. For rows 1 to 4, the respective limits are 0.431270..., 0.636059..., 3.229697..., 5.015914... .
EXAMPLE
Northwest corner:
2, 5, 13, 37, 109, 317, ...
3, 7, 19, 53, 157, 467, ...
11, 31, 89, 263, 787, 2357, ...
17, 47, 139, 409, 1223, 3659, ...
23, 67, 199, 593, 1777, 5323, ...
29, 83, 241, 719, 2153, 6451, ...
MATHEMATICA
seqL = 14; arr1[1] = {2}; Do[AppendTo[arr1[1], NextPrime[3*Last[arr1[1]], -1]], {seqL}]; Do[tmp = Union[Flatten[Map[arr1, Range[z]]]]; arr1[z] = {Prime[NestWhile[# + 1 &, 1, PrimePi[tmp[[#]]] - # == 0 &]]}; Do[AppendTo[arr1[z], NextPrime[3*Last[arr1[z]], -1]], {seqL}], {z, 2, 22}]; m = Map[arr1, Range[22]]; m // TableForm
t = Table[m[[n - k + 1]][[k]], {n, 12}, {k, n, 1, -1}] // Flatten (* Peter J. C. Moses, Sep 26 2013 *)
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Clark Kimberling, Sep 26 2013
EXTENSIONS
Incorrect comment deleted by Peter Munn, Aug 15 2017
STATUS
approved