a(n) is the number of 5 element sets of distinct integer-sided trapezoids whose base angles are 60 degrees that fill an equilateral triangular grid of side n units with a trapezoid filled by 3 trapezoids.
A391204
a(n) is the number of 5 element sets of distinct integer-sided trapezoids whose base angles are 60 degrees that fill an equilateral triangular grid of side n units with a trapezoid filled by 3 trapezoids.
Terms
- a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =0a(6) =6a(7) =24a(8) =53a(9) =115a(10) =200a(11) =332a(12) =520a(13) =782a(14) =1102a(15) =1553a(16) =2093a(17) =2769a(18) =3605a(19) =4623a(20) =5795a(21) =7248a(22) =8899a(23) =10818a(24) =13066a(25) =15639a(26) =18500a(27) =21858a(28) =25564a(29) =29714
External references
- oeis: A391204