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A175608
Characteristic function of squarefree triangular integers: 1 if n(n+1)/2 is squarefree else 0.
1
1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 1, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 1, 0, 0, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1
OFFSET
1,1
LINKS
FORMULA
a(n) = A008966(n(n+1)/2).
Asymptotic mean: lim_{n->oo} (1/n) * Sum_{k=1..n} a(k) = (3/2)*A065474 = 0.4839511484... . - Amiram Eldar, May 10 2022
MATHEMATICA
Table[If[SquareFreeQ[n(n+1)/2], 1, 0], {n, 200}]
If[SquareFreeQ[#], 1, 0]&/@Accumulate[Range[120]] (* Harvey P. Dale, Nov 22 2022 *)
CROSSREFS
Cf. A008966 (1 if n is squarefree, else 0), A010051 (Characteristic function of primes: 1 if n is prime else 0).
Sequence in context: A144778 A143142 A174856 * A285467 A194679 A111940
KEYWORD
nonn
AUTHOR
Zak Seidov, Jul 23 2010
STATUS
approved