A120700 a(n) is the least refactorable number k having the n-th prime as its greatest prime factor.

2, 9, 40, 56, 88, 104, 136, 152, 184, 232, 248, 296, 328, 344, 376, 424, 472, 488, 536, 568, 584, 632, 664, 712, 776, 808, 824, 856, 872, 904, 1016, 1048, 1096, 1112, 1192, 1208, 1256, 1304, 1336, 1384, 1432, 1448, 1528, 1544, 1576, 1592, 1688, 1784, 1816

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Mathematica

f[n_] := Block[{a = Mod[n, DivisorSigma[0, n]], b = PrimePi[FactorInteger[n][[ -1, 1]]]}, {a, b}]; t = Table[0, {100}]; Do[c = f[n]; If[c[[1]] == 0 && t[[c[[2]]]] == 0, t[[c[[2]]]] = n], {n, 2, 1831}]

Crossrefs

Cf. A033950, A036878.

Sequence in context: A096359 A020002 A346687 * A075873 A124722 A317129

Adjacent sequences: A120697 A120698 A120699 * A120701 A120702 A120703

Keyword

nonn

Author

Walter Kehowski and Robert G. Wilson v, Jun 28 2006

Status

approved