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.
%I A385291 #28 Aug 29 2025 20:56:07
%S A385291 1,1,1,1,2,1,1,6,3,1,1,19,15,4,1,1,63,86,28,5,1,1,216,534,234,45,6,1,
%T A385291 1,760,3481,2162,495,66,7,1,1,2725,23502,21272,6095,901,91,8,1,1,9910,
%U A385291 162913,218740,80617,13881,1484,120,9,1,1,36446,1152870,2323730,1121075,231008,27468,2276,153,10,1
%N A385291 Square array read by descending antidiagonals: A(n,k) is the number of fixed n-dimensional polyominoes of size k.
%H A385291 John Mason, <a href="/A385291/b385291.txt">Table of n, a(n) for n = 1..162</a>
%F A385291 A(n,k) = Sum_{d=0..n} binomial(n,d)*A195739(k,d) (with A195739(k,d) = 0 for k <= d). - _Pontus von Brömssen_, Jun 28 2025
%e A385291 The top corner of the array (size on horizontal axis, dimensions on vertical):
%e A385291 1: 1 1 1 1 1 1 1
%e A385291 (A001168) 2: 1 2 6 19 63 216 760
%e A385291 (A001931) 3: 1 3 15 86 534 3481 23502
%e A385291 (A151830) 4: 1 4 28 234 2162 21272 218740
%e A385291 (A151831) 5: 1 5 45 495 6095 80617 1121075
%e A385291 (A151832) 6: 1 6 66 901 13881 231008 4057660
%e A385291 (A151833) 7: 1 7 91 1484 27468 551313 11710328
%e A385291 (A151834) 8: 1 8 120 2276 49204 1156688 28831384
%e A385291 (A151835) 9: 1 9 153 3309 81837 2205489 63113061
%e A385291 10: 1 10 190 4615 128515 3906184 126210640
%e A385291 11: 1 11 231 6226 192786 6524265 234919234
%e A385291 12: 1 12 276 8174 278598 10389160 412504236
%e A385291 13: 1 13 325 10491 390299 15901145 690185431
%e A385291 14: 1 14 378 13209 532637 23538256 1108774772
%e A385291 15: 1 15 435 16360 710760 33863201 1720467820
%e A385291 16: 1 16 496 19976 930216 47530272 2590788848
%e A385291 17: 1 17 561 24089 1196953 65292257 3800689609
%e A385291 18: 1 18 630 28731 1517319 88007352 5448801768
%e A385291 19: 1 19 703 33934 1898062 116646073 7653842998
%e A385291 20: 1 20 780 39730 2346330 152298168 10557176740
%e A385291 21: 1 21 861 46151 2869671 196179529 14325525627
%e A385291 22: 1 22 946 53229 3476033 249639104 19153838572
%e A385291 23: 1 23 1035 60996 4173764 314165809 25268311520
%e A385291 24: 1 24 1128 69484 4971612 391395440 32929561864
%Y A385291 Cf. A000384 (column k=3), A195739.
%Y A385291 Rows: A000012 (n=1), A001168 (n=2), A001931 (n=3), A151830 (n=4), A151831 (n=5), A151832 (n=6), A151833 (n=7), A151834 (n=8), A151835 (n=9).
%K A385291 nonn,tabl,changed
%O A385291 1,5
%A A385291 _John Mason_, Jun 24 2025
%E A385291 a(56)-a(66) from _Pontus von Brömssen_, Jun 28 2025