A201011 -id:A201011 - cp's OEIS frontend

A201010 Integers that can be written as the product and/or quotient of Lucas numbers.

1, 2, 3, 4, 6, 7, 8, 9, 11, 12, 14, 16, 18, 19, 21, 22, 23, 24, 27, 28, 29, 31, 32, 33, 36, 38, 41, 42, 44, 46, 47, 48, 49, 54, 56, 57, 58, 62, 63, 64, 66, 69, 72, 76, 77, 81, 82, 84, 87, 88, 92, 93, 94, 96, 98, 99, 107, 108, 112, 114, 116, 121, 123, 124, 126, 128

Offset: 1

Arkadiusz Wesolowski, Jan 08 2013

These numbers do not occur in A178777.
The first 20 terms of this sequence are the same as in A004144 (nonhypotenuse numbers).
Integers of the form A200381(n)/A200381(m) for some m and n.

			19 is in the sequence because Lucas(9)/Lucas(0)^2 = 19.

Arkadiusz Wesolowski, Table of n, a(n) for n = 1..10000
Eric Weisstein's World of Mathematics, Lucas Number
Index entries for Lucas sequences

Cf. A000032, A200381, A200995, A201011. Subsequence of A178772. Complement of A201012.

maxTerm = 128; Clear[f]; f[lim_] := f[lim] = (luc = LucasL[Range[0, lim]]; luc = Delete[luc, 2];  last = luc[[-1]]; t = {1}; Do[t2 = luc[[n]]^Range[ Floor[ Log[last] / Log[ luc[[n]] ]]]; s = Select[ Union[ Flatten[ Outer[ Times, t, t2]]], # <= last &]; t = Union[t, s], {n, lim}]; maxIndex = Length[A200381 = t]; Reap[ Do[r = A200381[[n]] / A200381[[m]]; If[IntegerQ[r] && r <= maxTerm, Sow[r]], {n, 1, maxIndex}, {m, 1, maxIndex}]][[2, 1]] // Union); f[5]; f[lim = 10]; While[ Print["lim = ", lim]; f[lim] != f[lim-5], lim = lim+5]; f[lim] (* Jean-François Alcover, Jun 24 2015, after script by T. D. Noe in A200381 *)

A201012 Integers that cannot be written as the product and/or quotient of Lucas numbers.

Original entry on oeis.org

5, 10, 13, 15, 17, 20, 25, 26, 30, 34, 35, 37, 39, 40, 43, 45, 50, 51, 52, 53, 55, 59, 60, 61, 65, 67, 68, 70, 71, 73, 74, 75, 78, 79, 80, 83, 85, 86, 89, 90, 91, 95, 97, 100, 101, 102, 103, 104, 105, 106, 109, 110, 111, 113, 115, 117, 118, 119, 120, 122, 125, 127

Offset: 1