23840

Appears in sequences

• a(n) = floor(4th elementary symmetric function of Sum_{j=1..k} 1/j, k = 1,2,...,n).at n=9A025214
• Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 77.at n=29A031575
• Minimal peaks in digital expansions of Pi: positions of peaks equal to 1.at n=25A105275
• Sum of the squares of the first n squarefree numbers.at n=31A111715
• Number of base 20 circular n-digit numbers with adjacent digits differing by 3 or less.at n=5A125330
• Numbers k such that absolute value of 9^k - k^9 is prime.at n=5A128449
• Number of n X 4 binary arrays with every 1 having exactly two king-move neighbors equal to 1.at n=8A183445
• 1/128 the number of (n+2) X 3 binary arrays with each 3 X 3 subblock trace equal to some horizontal or vertical neighbor 3 X 3 subblock trace.at n=6A185985
• 1/128 the number of (n+2)X9 binary arrays with each 3X3 subblock trace equal to some horizontal or vertical neighbor 3X3 subblock trace.at n=0A185991
• T(n,k)=1/128 the number of (n+2)X(k+2) binary arrays with each 3X3 subblock trace equal to some horizontal or vertical neighbor 3X3 subblock trace.at n=21A185993
• T(n,k)=1/128 the number of (n+2)X(k+2) binary arrays with each 3X3 subblock trace equal to some horizontal or vertical neighbor 3X3 subblock trace.at n=27A185993
• The Wiener index of the comb-shaped graph |_|_|...|_| with 2n (n>=1) nodes. The Wiener index of a connected graph is the sum of the distances between all unordered pairs of vertices in the graph.at n=31A192023
• A256056(n)/2.at n=33A256055
• Number of unlabeled rooted trees with n nodes where the outdegrees (branching factors) of adjacent nodes differ by exactly one.at n=60A257654
• 50-gonal numbers: a(n) = 48*n*(n-1)/2 + n.at n=32A261343
• Number of n X n 0..1 arrays with every element equal to 1, 2, 3 or 5 king-move adjacent elements, with upper left element zero.at n=4A297944
• Number of nX5 0..1 arrays with every element equal to 1, 2, 3 or 5 king-move adjacent elements, with upper left element zero.at n=4A297948
• T(n,k)=Number of nXk 0..1 arrays with every element equal to 1, 2, 3 or 5 king-move adjacent elements, with upper left element zero.at n=40A297951
• Composite numbers whose sum of aliquot parts divide the sum of the squares of their aliquot parts.at n=39A301482