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A014795
Squares of odd tetrahedral numbers.
1
1, 1225, 27225, 207025, 938961, 3136441, 8555625, 20205025, 42837025, 83521321, 152300281, 262926225, 433680625, 688275225, 1056835081, 1576963521, 2294889025, 3266694025, 4559625625, 6253488241, 8442118161, 11234940025, 14758605225, 19158712225, 24601608801
OFFSET
0,2
FORMULA
From Amiram Eldar, Mar 07 2022: (Start)
a(n) = A015219(n)^2 = ((4*n+1)*(4*n+2)*(4*n+3)/6)^2.
Sum_{n>=0} 1/a(n) = 9*Pi*(Pi-3)/4. (End)
MATHEMATICA
Table[((4*n+1)*(4*n+2)*(4*n+3)/6)^2, {n, 0, 40}] (* Amiram Eldar, Mar 07 2022 *)
CROSSREFS
KEYWORD
nonn,easy
EXTENSIONS
More terms from Erich Friedman
More terms from Amiram Eldar, Mar 07 2022
STATUS
approved