25280

Appears in sequences

• a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n+1-k), where k = [ (n+1)/2 ], s = (composite numbers), t = (odd natural numbers).at n=42A024590
• Expansion of (theta_3(z)*theta_3(15z) + theta_2(z)*theta_2(15z))^4.at n=27A028628
• Euler transform of {1, primes}.at n=15A030012
• a(n) = a(1) + a(2) + ... + a(n-1) + a(m) for n >= 3, where m = n - 1 - 2^p and p is the unique integer such that 2^p < n - 1 <= 2^(p+1), starting with a(1) = a(2) = 1.at n=15A049942
• Number of distinct non-extendable sequences X={x(1),x(2),...,x(k)} where x(1)=1, the x(i)'s are distinct elements of {1,...,n} with |x(i)-x(i+1)|=1 or 2, for i=1,2,...,k.at n=16A054668
• Numbers k such that sigma(k^2-k-1) = k*(k+1).at n=31A069826
• a(n) = 4*(3*n+1)*(3*n+2).at n=26A144410
• Eight times hexagonal numbers: a(n) = 8*n*(2*n-1).at n=40A152750
• The Wiener index of the windmill graph D(6,n). The windmill graph D(m,n) is the graph obtained by taking n copies of the complete graph K_m with a vertex in common (i.e., a bouquet of n pieces of K_m graphs).at n=31A180577
• Number of (n+1)X(2+1) 0..3 arrays with the maximum plus the lower median minus the upper median minus the minimum of every 2X2 subblock differing from its horizontal and vertical neighbors by exactly one.at n=1A237540
• T(n,k)=Number of (n+1)X(k+1) 0..3 arrays with the maximum plus the lower median minus the upper median minus the minimum of every 2X2 subblock differing from its horizontal and vertical neighbors by exactly one.at n=4A237544
• Number of length n+3 0..7 arrays with no four consecutive terms having the sum of any three elements equal to three times the fourth.at n=1A249289
• T(n,k) = Number of length n+3 0..k arrays with no four consecutive terms having the sum of any three elements equal to three times the fourth.at n=29A249290
• Number of length 2+3 0..n arrays with no four consecutive terms having the sum of any three elements equal to three times the fourth.at n=6A249292
• Number of (n+2)X(n+2) 0..3 arrays with every 3X3 subblock row and diagonal sum equal to 0 2 3 6 or 7 and every 3X3 column and antidiagonal sum not equal to 0 2 3 6 or 7.at n=6A252524
• Number of (n+2) X (7+2) 0..3 arrays with every 3 X 3 subblock row and diagonal sum equal to 0 2 3 6 or 7 and every 3 X 3 column and antidiagonal sum not equal to 0 2 3 6 or 7.at n=6A252531
• Number of (7+2) X (n+2) 0..3 arrays with every 3 X 3 subblock row and diagonal sum equal to 0 2 3 6 or 7 and every 3 X 3 column and antidiagonal sum not equal to 0 2 3 6 or 7.at n=6A252539
• Number of n X 1 0..2 arrays with no element equal to a strict majority of its king-move neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards.at n=11A279322
• Number of n X 2 0..2 arrays with no element equal to a strict majority of its horizontal and antidiagonal neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards.at n=5A279574
• T(n,k)=Number of nXk 0..2 arrays with no element equal to a strict majority of its horizontal and antidiagonal neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards.at n=26A279580