A087429 a(n) = 1 if gpf(n) < gpf(n+1), otherwise 0, where gpf = A006530 (greatest prime factor).

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

Offset

1,1

Comments

Equivalently, a(n) = 1 iff A061395(n+1) > A061395(n), otherwise a(n) = 0. - Giovanni Teofilatto, Jan 03 2008

Links

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

Index entries for characteristic functions

Formula

a(n) = A057427(1+A057427(A070221(n))).

a(p-1)=1 and a(p)=0 for primes p.

a(A070089(n)) = 1, a(A070087(n)) = 0, a(A087430(n)) = 0.

Mathematica

Join[{1}, Table[If[PrimePi[FactorInteger[n + 1][[ -1, 1]]] > PrimePi[FactorInteger[n][[ -1, 1]]], 1, 0], {n, 2, 90}]] (* Stefan Steinerberger, Jan 06 2008 *)
If[#[[1]]<#[[2]], 1, 0]&/@Partition[FactorInteger[#][[-1, 1]]&/@Range[120], 2, 1] (* Harvey P. Dale, Nov 19 2023 *)

Crossrefs

Characteristic function of A070089.

Cf. A006530, A057427, A061395, A070087, A070221, A087430.

Sequence in context: A347950 A105470 A359824 * A093075 A104120 A254634

Adjacent sequences: A087426 A087427 A087428 * A087430 A087431 A087432

Keyword

nonn

Author

Reinhard Zumkeller, Sep 02 2003

Extensions

Edited by N. J. A. Sloane, Jul 01 2008, at the suggestion of R. J. Mathar

Status

approved