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This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A220516 Nonnegative integers in square maze arrangement T(n,k), read by antidiagonals, n>=0, k>=0.

Original entry on oeis.org

0, 1, 3, 8, 2, 4, 9, 7, 5, 15, 24, 10, 6, 14, 16, 25, 23, 11, 13, 17, 35, 48, 26, 22, 12, 18, 34, 36, 49, 47, 27, 21, 19, 33, 37, 63, 80, 50, 46, 28, 20, 32, 38, 62, 64, 81, 79, 51, 45, 29, 31, 39, 61, 65, 99, 120, 82, 78, 52, 44, 30, 40, 60, 66, 98, 100
Offset: 0

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Author

Omar E. Pol, Feb 09 2013

Keywords

Comments

This sequence consists of 0 together with a permutation of the natural numbers. The structure is the same as A081344 but starting with 0, not 1.
It appears that in the n-th layer there is at least a prime number <= g and also there is at least a prime number > g, where g is the number on the main diagonal, the n-th oblong number A002378(n), if n >= 1.

Examples

			The first layer is [1, 2, 3] which looks like this:
.  3,
1, 2,
The second layer is [4, 5, 6, 7, 8] which looks like this:
.  .  4
.  .  5,
8, 7, 6,
Square array T(0,0)..T(10,10) begins:
0,     3,   4,  15,  16,  35,  36,  63,  64,  99, 100,...
1,     2,   5,  14,  17,  34,  37,  62,  65,  98, 101,...
8,     7,   6,  13,  18,  33,  38,  61,  66,  97, 102,...
9,    10,  11,  12,  19,  32,  39,  60,  67,  96, 103,...
24,   23,  22,  21,  20,  31,  40,  59,  68,  95, 104,...
25,   26,  27,  28,  29,  30,  41,  58,  69,  94, 105,...
48,   47,  46,  45,  44,  43,  42,  57,  70,  93, 106,...
49,   50,  51,  52,  53,  54,  55,  56,  71,  92, 107,...
80,   79,  78,  77,  76,  75,  74,  73,  72,  91, 108,...
81,   82,  83,  84,  85,  86,  87,  88,  89,  90, 109,...
120, 119, 118, 117, 116, 115, 114, 113, 112, 111, 110,...
...
		

Crossrefs

Main diagonal is A002378.

Formula

a(n) = A081344(n+1) - 1.
T(n,k) = n^2 + k , if n is odd and k<=n.
T(n,k) = n(n + 2) - k, if n is even and k<=n.
T(n,k) = k(k + 2) - n, if n is odd and n
T(n,k) = k^2 + n , if n is even and n