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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.

A303990 Triangle, read by rows: n^k * k^n, for n >= 1 and k = 1..n.

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%I A303990 #19 Sep 08 2022 08:46:21
%S A303990 1,2,16,3,72,729,4,256,5184,65536,5,800,30375,640000,9765625,6,2304,
%T A303990 157464,5308416,121500000,2176782336,7,6272,750141,39337984,
%U A303990 1313046875,32934190464,678223072849,8,16384,3359232,268435456,12800000000,440301256704,12089663946752,281474976710656
%N A303990 Triangle, read by rows: n^k * k^n, for n >= 1 and k = 1..n.
%C A303990 Due to the symmetry of n^k * k^n under the exchange n <-> k, it is sufficient to consider n >= 1, and k = 1..n.
%C A303990 For the array n^k * k^n, with n >= 0 and k >= 0, read by antidiagonals, see the triangle A062275.
%C A303990 Thanks go to S. Heinemeyer for leading me to look at this.
%C A303990 The row sums give A303991.
%F A303990 T(n, k) = n^k * k^n, for n >= 1, k = 1..n.
%e A303990 The triangle T(n, k) begins:
%e A303990 ======================================================================
%e A303990 n\k |  1    2      3        4          5           6            7  ...
%e A303990 ----+-----------------------------------------------------------------
%e A303990 1:  |  1
%e A303990 2:  |  2   16
%e A303990 3:  |  3   72    729
%e A303990 4:  |  4  256   5184    65536
%e A303990 5:  |  5  800  30375   640000    9765625
%e A303990 6:  |  6 2304 157464  5308416  121500000  2176782336
%e A303990 7:  |  7 6272 750141 39337984 1313046875 32934190464 678223072849
%e A303990 ...
%e A303990 row n=8: 8, 16384, 3359232, 268435456, 12800000000, 440301256704, 12089663946752, 281474976710656;
%e A303990 row n=9: 9, 41472, 14348907, 1719926784, 115330078125, 5355700839936, 193010051319183, 5777633090469888, 150094635296999121;
%e A303990 row n=10: 10, 102400, 59049000, 10485760000, 976562500000, 60466176000000, 2824752490000000, 107374182400000000, 3486784401000000000, 100000000000000000000;
%e A303990 ...
%t A303990 Table[n^k k^n, {n, 10}, {k, n}] //Flatten (* _Vincenzo Librandi_, May 23 2018 *)
%o A303990 (Magma) /* As triangle */ [[n^k*k^n: k in [1..n]]: n in [1.. 15]]; // _Vincenzo Librandi_, May 23 2018
%o A303990 (PARI) T(n, k) = n^k * k^n;
%o A303990 tabl(nn) = for (n=1, nn, for (k=1, n, print1(T(n, k), ", ")); print); \\ _Michel Marcus_, May 25 2018
%Y A303990 Cf. A062275, A303991.
%K A303990 nonn,tabl,easy
%O A303990 1,2
%A A303990 _Wolfdieter Lang_, May 22 2018