21530

Appears in sequences

• Numbers that contain as proper substrings every maximal prime power dividing them.at n=10A059401
• Expansion of 1/(1-2*x-3*x^2-2*x^3).at n=9A077833
• Numbers n such that sigma(n)=2n-phi(phi(n)).at n=17A110073
• Number of permutations of length n which avoid the patterns 312, 1324, 3421; or avoid the patterns 312, 1324, 2341, etc.at n=27A116722
• Number of nondecreasing arrangements of 6 numbers x(i) in -(n+4)..(n+4) with the sum of sign(x(i))*2^|x(i)| zero.at n=39A187990
• Number of nX5 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 2,2,1,1,1 for x=0,1,2,3,4.at n=7A197542
• Number of partitions p of n not including floor(mean(p)) as a part.at n=42A241335
• Number of (n+2)X(n+2) 0..1 arrays with every 3X3 subblock sum of the two medians of the central row and the central column and the two maximums of the diagonal and antidiagonal nondecreasing horizontally and vertically.at n=1A254353
• Number of (n+2)X(2+2) 0..1 arrays with every 3X3 subblock sum of the two medians of the central row and the central column and the two maximums of the diagonal and antidiagonal nondecreasing horizontally and vertically.at n=1A254355
• T(n,k)=Number of (n+2)X(k+2) 0..1 arrays with every 3X3 subblock sum of the two medians of the central row and the central column and the two maximums of the diagonal and antidiagonal nondecreasing horizontally and vertically.at n=4A254361
• Pierce Expansion of cot(1).at n=17A280094