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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.

A223870 Number of 7Xn 0..3 arrays with rows and antidiagonals unimodal and columns nondecreasing.

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%I A223870 #6 Jul 23 2025 04:36:55
%S A223870 120,14400,857696,30627033,740441932,13140481520,181330154458,
%T A223870 2031375254570,19103100564953,154879319818086,1106319655331310,
%U A223870 7088499061347994,41355557480132029,222496813189773094
%N A223870 Number of 7Xn 0..3 arrays with rows and antidiagonals unimodal and columns nondecreasing.
%C A223870 Row 7 of A223864
%H A223870 R. H. Hardin, <a href="/A223870/b223870.txt">Table of n, a(n) for n = 1..210</a>
%F A223870 Empirical: a(n) = (1/731743016283032599871082788290560000000)*n^42 + (1/4977843648183895237218250260480000000)*n^41 + (928393/46001848566932971411483888975872000000000)*n^40 + (105277/73145796479098389325092394893312000000)*n^39 + (1194875887417/14630003285779052077202999275526553600000000)*n^38 + (2989034162869/770000172935739583010684172396134400000000)*n^37 + (253954581560803/1578153507593520316530906749730816000000000)*n^36 + (5354203220243/901802004339154466589089571274752000000)*n^35 + (294541461227512613/1487973307159604869871997792603340800000000)*n^34 + (3283448634973867/543651190047352893632443475558400000000)*n^33 + (1695440335227801901/9946345636093615440320840859648000000000)*n^32 + (3573106388063476091/795707650887489235225667268771840000000)*n^31 + (199763950144059168991/1796759211681427305348280929484800000000)*n^30 + (74264834838952433551/28519987487006782624575887769600000000)*n^29 + (22508587327587010087/388203096465609563855388672000000000)*n^28 + (6487713317681801287/5268470594890415509465989120000000)*n^27 + (5879724305315631273143/236027482651090614824076312576000000)*n^26 + (2274008762771343921151/4777884264192117708989399040000000)*n^25 + (1433958075984913204598868559/170382339038756037576130088140800000000)*n^24 + (171994077476794008378711763/1298151154580998381532419719168000000)*n^23 + (4807317857591109327659320591/2616826438088178555658237378560000000)*n^22 + (1168312336634046874744823561/53404621185473031748127293440000000)*n^21 + (3267005930489620041151124845704799/14294414418056675360283121680384000000000)*n^20 + (6168875562195824331118939779649/3009350403801405339006972985344000000)*n^19 + (1421349779115626568528007952265121/87772720110874322387703378739200000000)*n^18 + (443650330465794505186411456583/4008618930894881365898035200000000)*n^17 + (231458296026946241960005215879167/345743382789683517808705536000000000)*n^16 + (2781803526486270651769956719311/790270589233562326419898368000000)*n^15 + (180518342530030480992731139435779501/11029213910990904218097706598400000000)*n^14 + (112422850223626902402310801373206057/1696802140152446802784262553600000000)*n^13 + (256455030218680186741984545055085811457/1087881553947739188785091969024000000000)*n^12 + (10923760852985777320434335065266037/15015618411977076449759723520000000)*n^11 + (88612710087482886643695234551735533/45442003088877994519009689600000000)*n^10 + (5132272050632981323250919168852481/1142060924191378169128550400000000)*n^9 + (176762144080638309567478939777189963/19986066173349117959749632000000000)*n^8 + (12877453273843085031374115529301/876581849708294647357440000000)*n^7 + (93032030615999750514907250146925549/4583262987565425332123834880000000)*n^6 + (60616255337563316970152218520251/2645462041884805386507264000000)*n^5 + (94214291470099334061118441477637/4572870100972306453819699200000)*n^4 + (66435080638421714121718489/4652899980639302456064000)*n^3 + (385110153135599654276494759/50995582363565168801472000)*n^2 + (169896669668551379/73020063246530400)*n + 1
%e A223870 Some solutions for n=3
%e A223870 ..0..0..0....0..0..0....0..0..0....0..0..0....0..0..0....0..0..0....0..0..0
%e A223870 ..0..0..0....0..0..0....0..0..0....0..0..2....0..0..0....0..2..0....0..0..0
%e A223870 ..0..0..1....0..0..1....0..0..3....1..2..3....2..0..0....0..2..1....0..0..1
%e A223870 ..1..1..2....0..0..2....0..1..3....1..3..3....2..0..0....1..2..1....2..3..1
%e A223870 ..2..2..2....0..2..3....0..1..3....1..3..3....3..1..0....3..2..2....3..3..1
%e A223870 ..3..2..2....1..2..3....1..1..3....1..3..3....3..1..0....3..2..2....3..3..1
%e A223870 ..3..3..2....2..3..3....1..3..3....3..3..3....3..3..2....3..2..2....3..3..3
%K A223870 nonn
%O A223870 1,1
%A A223870 _R. H. Hardin_ Mar 28 2013