A119885 -id:A119885 - cp's OEIS frontend

A119911 Natural numbers with number of divisors not equal to a Lucas number.

12, 16, 18, 20, 24, 28, 30, 32, 36, 40, 42, 44, 45, 48, 50, 52, 54, 56, 60, 63, 66, 68, 70, 72, 75, 76, 78, 80, 81, 84, 88, 90, 92, 96, 98, 99, 100, 102, 104, 105, 108, 110, 112, 114, 116, 117, 120, 124, 126, 128, 130, 132, 135, 136, 138, 140, 144, 147, 148

Offset: 1

Giovanni Teofilatto, Aug 02 2006

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

Cf. A000032.

Complement to A119885.

With[{lnos=LucasL[Range[0,20]]},Select[Range[300],!MemberQ[ lnos, DivisorSigma[ 0,#]]&]] (* Harvey P. Dale, May 11 2014 *)

More terms from Harvey P. Dale, May 11 2014

A123927 Characteristic function of natural numbers with number of divisors equal to a Lucas number.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 0, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 0, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1, 0, 0, 0, 1, 0, 1

Offset: 1

Giovanni Teofilatto, Nov 22 2006

Cf. A000005, A102460, A119885, A119911, A122895.

With[{nn = 103}, Table[Boole[MemberQ[#, DivisorSigma[0, n]]], {n, nn}] &@ TakeWhile[Union@ Array[LucasL, 40, 0], # <= nn &]] (* Michael De Vlieger, Nov 22 2017 *)

A102460(n) = { my(u1=1,u2=3,old_u1); if(n<=2,sign(n),while(n>u2,old_u1=u1;u1=u2;u2=old_u1+u2);(u2==n)); };
A123927(n) = A102460(numdiv(n)); \\ Antti Karttunen, Nov 22 2017

a(n) = A102460(A000005(n)). - Antti Karttunen, Nov 22 2017

Superfluous 0 at the beginning of data removed by Antti Karttunen, Nov 22 2017

cp's OEIS Frontend

A119911 Natural numbers with number of divisors not equal to a Lucas number.

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