A005722 a(n) = (prime(n) - 1)^2.
1, 4, 16, 36, 100, 144, 256, 324, 484, 784, 900, 1296, 1600, 1764, 2116, 2704, 3364, 3600, 4356, 4900, 5184, 6084, 6724, 7744, 9216, 10000, 10404, 11236, 11664, 12544, 15876, 16900, 18496, 19044, 21904, 22500, 24336, 26244, 27556, 29584, 31684, 32400, 36100
Offset: 1
Links
- Vincenzo Librandi, Table of n, a(n) for n = 1..1000
- Richard K. Guy, Letter to N. J. A. Sloane, 1987.
Programs
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Magma
[(p-1)^2: p in PrimesUpTo(200)]; // Vincenzo Librandi, Mar 27 2014
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Maple
A005722:=n->(ithprime(n)-1)^2; seq(A005722(n), n=1..40); # Wesley Ivan Hurt, Mar 27 2014
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Mathematica
Table[(Prime[n] - 1)^2, {n, 40}] (* Vincenzo Librandi, Mar 27 2014 *) -
PARI
a(n) = (prime(n) - 1)^2; \\ Michel Marcus, Nov 09 2020
Formula
a(n) = A006093(n)^2. - Wesley Ivan Hurt, Mar 27 2014
Sum_{n>=1} 1/a(n) = A086242. - Amiram Eldar, Nov 09 2020
From Amiram Eldar, Jan 23 2021: (Start)
Product_{n>=1} (1 + 1/a(n)) = A065485.
Product_{n>=2} (1 - 1/a(n)) = A005597. (End)