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 A049735 Array T(i,j) is the number of lattice points (x,y) in circle with radius (0,0)-to-(i,j), read by antidiagonals. 10
 1, 5, 5, 13, 9, 13, 29, 21, 21, 29, 49, 37, 25, 37, 49, 81, 57, 45, 45, 57, 81, 113, 89, 69, 61, 69, 89, 113, 149, 121, 97, 81, 81, 97, 121, 149, 197, 161, 129, 109, 101, 109, 129, 161, 197, 253, 213, 177, 145, 137, 137, 145, 177, 213, 253 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Specifically, x^2 + y^2 <= i^2 + j^2. LINKS FORMULA T(n,0) = A000328(n). EXAMPLE Antidiagonals (each starting on row 0): {1}, {5, 5}, {13, 9, 13}, ... Array begins: 1 5 13 29 49 81 5 9 21 37 57 89 13 21 25 45 69 97 29 37 45 61 81 109 49 57 69 81 101 137 81 89 97 109 137 161 PROG (PARI) T(n, k) = my(z=norml2([n, k]), m=ceil(sqrt(2)*max(n, k))); sum(x=-m, m, sum(y=-m, m, norml2([x, y]) <= z)); \\ Michel Marcus, Aug 07 2021 CROSSREFS Cf. A000328 (1st column or row). Sequence in context: A206553 A122213 A224067 * A055526 A146984 A055524 Adjacent sequences: A049732 A049733 A049734 * A049736 A049737 A049738 KEYWORD nonn,tabl AUTHOR STATUS approved

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Last modified March 29 16:13 EDT 2023. Contains 361599 sequences. (Running on oeis4.)