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

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

1,1

Links

Antti Karttunen, Table of n, a(n) for n = 1..65537

Index entries for characteristic functions

Index entries for sequences computed from exponents in factorization of n

Formula

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

Mathematica

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

Prog

(PARI)
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

Crossrefs

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

Sequence in context: A354923 A354924 A353799 * A089829 A294935 A242902

Adjacent sequences: A123924 A123925 A123926 * A123928 A123929 A123930

Keyword

easy,nonn

Author

Giovanni Teofilatto, Nov 22 2006

Extensions

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

Status

approved