19880

Appears in sequences

• First differences of A037260.at n=41A037261
• Engel expansion of sinh(1/2).at n=35A068379
• Numbers k such that sigma(k^2-k-1) = k*(k+1).at n=26A069826
• Triangle read by rows: S_B(n,k) = "Type B" Stirling numbers of the second kind.at n=25A085483
• Triangle read by rows: T(n,k) is the number of binary trees (i.e., a rooted tree where each vertex has either 0, 1, or 2 children; and, when only one child is present, it is either a right child or a left child) with n edges and k pairs of adjacent vertices of outdegree 2.at n=23A126219
• a(n) = 4*(3*n+1)*(3*n+2).at n=23A144410
• a(n) = 686*n - 14.at n=28A157363
• E.g.f.: Sum_{n>=0} 1/n! * Product_{k=1..n} -log(1-x^k).at n=8A202203
• Number of (n+2)X4 binary arrays avoiding patterns 000 and 111 in rows, columns and nw-to-se diagonals.at n=4A202641
• Number of (n+2)X7 binary arrays avoiding patterns 000 and 111 in rows, columns and nw-to-se diagonals.at n=1A202644
• T(n,k)=Number of (n+2)X(k+2) binary arrays avoiding patterns 000 and 111 in rows, columns and nw-to-se diagonals.at n=16A202647
• T(n,k)=Number of (n+2)X(k+2) binary arrays avoiding patterns 000 and 111 in rows, columns and nw-to-se diagonals.at n=19A202647
• Number of (n+2) X 8 0..2 arrays with every 3 X 3 subblock having three equal elements in a row horizontally, vertically or nw-to-se diagonally exactly three ways, and new values 0..2 introduced in row major order.at n=7A204368
• a(1)=a(2)=0; thereafter a(n) = a(n-2)+A238828(n-1)+A238827(n).at n=14A238830
• Numbers m such that the GCD of the x's that satisfy sigma(x) = m is 3.at n=33A241648
• Numbers k such that 11^phi(k) == 1 (mod k^2), where phi(k) = A000010(k).at n=21A253016
• Number of regions into which a figure made up of a row of n adjacent congruent rectangles is divided upon drawing diagonals of all possible rectangles (a(0)=0 by convention).at n=18A306302
• Number of non-double-crossing set partitions of {1,...,n}.at n=9A306551
• Sum of the largest parts of the partitions of n into 5 parts.at n=40A308827
• Numbers k such that A011772(k) > A344878(k) and A011772(k) is a divisor of A344875(k).at n=16A344595