1,1

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

A007895(a(n)) = 3. - Reinhard Zumkeller, Mar 10 2013

12 = 1+3+8;

17 = 1+3+13;

19 = 1+5+13;

20 = 2+5+13;

25 = 21+3+1;

with(combinat): B := proc (n) local A, ct, m, j: A := proc (n) local i: for i while fibonacci(i) <= n do n-fibonacci(i) end do end proc: ct := 0: m := n: for j while 0 < A(m) do ct := ct+1: m := A(m) end do: ct+1 end proc: Q := {}: for i from fibonacci(7)-1 to 160 do if B(i) = 3 then Q := `union`(Q, {i}) else end if end do: Q

zeck = DigitCount[Select[Range[2000], BitAnd[#, 2*#] == 0 &], 2, 1];

Position[zeck, 3] // Flatten (* Jean-François Alcover, Jan 30 2018 *)

(Haskell)

a179243 n = a179243_list !! (n-1)

a179243_list = filter ((== 3) . a007895) [1..]

-- Reinhard Zumkeller, Mar 10 2013

(Python)

from math import comb, isqrt

from sympy import fibonacci, integer_nthroot

def A179243(n): return fibonacci(2+(r:=n-1-comb((m:=integer_nthroot(6*n, 3)[0])+(t:=(n>comb(m+2, 3)))+1, 3))-comb((k:=isqrt(b:=r+1<<1))+(b>k*(k+1)), 2))+fibonacci((a:=isqrt(s:=n-comb(m-(t^1)+2, 3)<<1))+((s<<2)>(a<<2)*(a+1)+1)+3)+fibonacci(m+t+5) # Chai Wah Wu, Apr 09 2025

Cf. A035517, A007895, A179242, A179244, A179245, A179246, A179247, A179248, A179249, A179250, A179251, A179252, A179253.

Sequence in context: A087657 A248478 A059390 * A350686 A064825 A162918

Adjacent sequences: A179240 A179241 A179242 * A179244 A179245 A179246

nonn,look

Emeric Deutsch, Jul 05 2010

approved