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URL: https://oeis.org/A212412

⇱ A212412 - OEIS

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A212412
Parity of curling number of binary expansion of n.
5
1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 1
OFFSET
0
FORMULA
a(n) = A181935(n) mod 2.
a(A212440(n)) = 0 and a(A212441(n)) = 1.
A212439(n) = 2*n + a(n).
a(n) = A000035(A181935(n)). - Omar E. Pol, Oct 28 2013
MATHEMATICA
f[n_, e_] := Module[{d = IntegerDigits[n, 2^e]}, Length[Split[d][[-1]]] - If[SameQ @@ d && Mod[n, 2^e] < 2^(e - 1), 1, 0]]; a[n_] := Mod[Max[Table[f[n, e], {e, Range[Max[1, Floor[Log2[n]]]]}]], 2]; a[0] = 1; Array[a, 100, 0] (* Amiram Eldar, Apr 08 2025 *)
PROG
(Haskell)
a212412 = (`mod` 2) . a181935
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Reinhard Zumkeller, May 17 2012
STATUS
approved