18860

Appears in sequences

• a(n) = Sum_{h=0..n, k=0..n} T(h,k), array T counting knights' moves as in A049604.at n=36A047881
• Truncated triangular pyramid numbers: a(n) = Sum_{k=9..n} (k*(k+1)/2 - 45).at n=40A051943
• a(n) = T(n,n-5), array T as in A055807.at n=20A055810
• Sum of absolute values of coefficients of expansion of (1-x)(1-x^2)(1-x^3)...(1-x^n).at n=38A061553
• a(n) = floor(sqrt(Fibonacci(n+1)) - sqrt(Fibonacci(n))).at n=48A063595
• Magnetic Tower of Hanoi, total number of moves, optimally solving the [RED ; NEUTRAL ; NEUTRAL] or [NEUTRAL ; NEUTRAL ; BLUE] pre-colored puzzle.at n=10A183116
• Number of 3-turn bishop's tours on an n X n board summed over all starting positions.at n=10A188778
• 23 times triangular numbers.at n=40A195039
• Number of 2 X 2 matrices having all elements in {-n,...n} and determinant 4.at n=33A209988
• Consider the nontrivial zeros of the Riemann zeta function on the critical line 1/2 + i*t and the gap, or first difference, between two consecutive such zeros; a(n) is the lesser of the two zeros at a place where the gap attains a new minimum.at n=28A254297
• Number of ways to move elements of an nXnXn triangular array to themselves or a neighbor, with no 2-cycles and with no more than 6-1 elements moved to themselves.at n=4A271850
• T(n,k)=Number of ways to move elements of an nXnXn triangular array to themselves or a neighbor, with no 2-cycles and with no more than k-1 elements moved to themselves.at n=49A271852
• a(n) = Sum_{k=0..7} (n + k)^2.at n=45A276026
• Expansion of Product_{k>=1} (1 + 2*x^k - x^(2*k)).at n=43A293182
• Number of compositions (ordered partitions) of n into centered hexagonal numbers (A003215).at n=46A322802
• a(n) = Sum_{k=1..n} binomial(k+2,2) * floor(n/k).at n=42A366984
• a(n) is the number of 4 element sets of distinct integer sided trapezoids whose base angles are 60 degrees that fill an equilateral triangular grid of side n units.at n=45A389392