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A123927 Characteristic function of natural numbers with number of divisors equal to a Lucas number. 2
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 (list; graph; refs; listen; history; text; internal format)
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: A014295 A228710 A103447 * 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

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Last modified November 19 22:34 EST 2019. Contains 329323 sequences. (Running on oeis4.)