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#71 by Joerg Arndt at Thu Dec 14 05:57:53 EST 2023
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#70 by Joerg Arndt at Thu Dec 14 05:57:44 EST 2023
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| FORMULA
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a(n) = -1 + Sum_{k=0..n} ((8*(sin(2*Pi*k/5))^2-5)^2-5)/20, with n>=0. a(n)= -1 + Sum_{k=0..n} (1/50)*(-9*(k mod 5) + ((n+1) mod 5) + ((n+2) mod 5) + ((n+3) mod 5) + 11*((n+4) mod 5)), with n >= 0. - Paolo P. Lava, May 15 2007
Also, floor((n^5-1)/5*n^4) will produce this sequence. Moreover, floor((n^5-n^4)/(5*n^4-4*n^3)) (n >= 1) will produce this sequence as well. - Mohammad K. Azarian, Nov 08 2007
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| STATUS
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approved
editing
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#69 by Michael De Vlieger at Tue Nov 08 13:58:25 EST 2022
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#68 by Michel Marcus at Tue Nov 08 11:53:52 EST 2022
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#67 by Chai Wah Wu at Tue Nov 08 10:57:57 EST 2022
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#66 by Chai Wah Wu at Tue Nov 08 10:57:30 EST 2022
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| PROG
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(Python)
def A002266(n): return n//5 # Chai Wah Wu, Nov 08 2022
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| STATUS
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approved
editing
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#65 by Michael De Vlieger at Fri Sep 30 07:47:20 EDT 2022
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#64 by Joerg Arndt at Fri Sep 30 05:59:56 EDT 2022
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#63 by Amiram Eldar at Fri Sep 30 04:30:08 EDT 2022
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#62 by Amiram Eldar at Fri Sep 30 04:14:48 EDT 2022
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Sum_{n>=5} (-1)^(n+1)/a(n) = log(2) (A002162). - Amiram Eldar, Sep 30 2022
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| CROSSREFS
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Cf. A002162, A008648, A004526, A002264, A002265, A010761, A010762, A110532, A110533, A010872, A010873, A010874.
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| STATUS
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approved
editing
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