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A087429
a(n) = 1 if gpf(n) < gpf(n+1), otherwise 0, where gpf = A006530 (greatest prime factor).
4
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
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.
Sequence in context: A347950 A105470 A359824 * A093075 A104120 A254634
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