The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A321391 Array read by antidiagonals: T(n,k) is the number of achiral rows of n colors using up to k colors. 7
 1, 1, 0, 1, 1, 0, 1, 2, 1, 0, 1, 3, 2, 1, 0, 1, 4, 3, 4, 1, 0, 1, 5, 4, 9, 4, 1, 0, 1, 6, 5, 16, 9, 8, 1, 0, 1, 7, 6, 25, 16, 27, 8, 1, 0, 1, 8, 7, 36, 25, 64, 27, 16, 1, 0, 1, 9, 8, 49, 36, 125, 64, 81, 16, 1, 0, 1, 10, 9, 64, 49, 216, 125, 256, 81, 32, 1, 0 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 0,8 COMMENTS The antidiagonals go from top-right to bottom-left. LINKS FORMULA T(n,k) = [n==0] + [n>0] * k^ceiling(n/2). The generating function for column k is (1+k*x) / (1-k*x^2). EXAMPLE The array begins with T(0,0): 1 1  1   1    1     1     1      1      1      1       1       1 ... 0 1  2   3    4     5     6      7      8      9      10      11 ... 0 1  2   3    4     5     6      7      8      9      10      11 ... 0 1  4   9   16    25    36     49     64     81     100     121 ... 0 1  4   9   16    25    36     49     64     81     100     121 ... 0 1  8  27   64   125   216    343    512    729    1000    1331 ... 0 1  8  27   64   125   216    343    512    729    1000    1331 ... 0 1 16  81  256   625  1296   2401   4096   6561   10000   14641 ... 0 1 16  81  256   625  1296   2401   4096   6561   10000   14641 ... 0 1 32 243 1024  3125  7776  16807  32768  59049  100000  161051 ... 0 1 32 243 1024  3125  7776  16807  32768  59049  100000  161051 ... 0 1 64 729 4096 15625 46656 117649 262144 531441 1000000 1771561 ... For T(3,3)=9, the rows are AAA, ABA, ACA, BAB, BBB, BCB, CAC, CBC, and CCC. MATHEMATICA Table[If[n>0, (n-k)^Ceiling[k/2], 1], {n, 0, 12}, {k, 0, n}] // Flatten CROSSREFS Columns 0-6 are A000007, A000012, A060546, A056449, A056450, A056451, A056452. Cf. A003992 (oriented), A277504 (unoriented), A293500 (chiral). Sequence in context: A301504 A307432 A256140 * A244003 A332670 A118344 Adjacent sequences:  A321388 A321389 A321390 * A321392 A321393 A321394 KEYWORD nonn,easy,tabl AUTHOR Robert A. Russell, Nov 08 2018 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified January 19 16:16 EST 2021. Contains 340270 sequences. (Running on oeis4.)