21537

Appears in sequences

• 30 'Reverse and Add' steps are needed to reach a palindrome.at n=6A065319
• Number of compositions of n+2 having exactly two parts equal to 1.at n=17A105423
• Number of 0..n arrays x(0..5) of 6 elements with zero 4th differences.at n=25A200084
• Number of (n+2)X(n+2) 0..1 arrays with every 3X3 subblock having three equal elements in a row horizontally, vertically or nw-to-se diagonally, and new values 0..1 introduced in row major order.at n=1A205265
• Number of (n+2) X 4 0..1 arrays with every 3 X 3 subblock having three equal elements in a row horizontally, vertically or nw-to-se diagonally, and new values 0..1 introduced in row major order.at n=1A205267
• T(n,k)=Number of (n+2)X(k+2) 0..1 arrays with every 3X3 subblock having three equal elements in a row horizontally, vertically or nw-to-se diagonally, and new values 0..1 introduced in row major order.at n=4A205273
• Number of singular 2 X 2 matrices having all elements in {-n,...,n}.at n=22A209981
• Numbers with 3 or more prime factors (with multiplicity) such that every concatenation of their prime factors is prime.at n=26A217264
• Number of partitions of n such that 2*(least part) <= greatest part.at n=36A237821
• Number of (n+2) X (1+2) 0..1 arrays with each 3 X 3 subblock having clockwise perimeter pattern 00010101 00101011 or 01010101.at n=12A260920
• Numbers k such that 32771*2^k + 1 is prime.at n=32A281483
• Number of nX5 0..1 arrays with every element equal to 2, 3, 4 or 7 king-move adjacent elements, with upper left element zero.at n=5A298130
• Number of nX6 0..1 arrays with every element equal to 2, 3, 4 or 7 king-move adjacent elements, with upper left element zero.at n=4A298131
• T(n,k)=Number of nXk 0..1 arrays with every element equal to 2, 3, 4 or 7 king-move adjacent elements, with upper left element zero.at n=49A298133
• T(n,k)=Number of nXk 0..1 arrays with every element equal to 2, 3, 4 or 7 king-move adjacent elements, with upper left element zero.at n=50A298133
• Terms k of A228058 such that gcd(k - A048250(k), A162296(k) - k) = A162296(k) - k.at n=33A325376
• Number of unlabeled loopless multigraphs with n edges covering four vertices.at n=32A328652
• Number of regions among all distinct circles that can be constructed from n equally spaced points along a line using only a compass.at n=16A359253
• Odd composites k such that sigma(k) has the same powerful part as k, where sigma is the sum of divisors function.at n=19A386425