19049

Appears in sequences

• Composite numbers whose prime factors contain no digits other than 3 and 4.at n=24A036314
• Diagonally symmetric n-celled polyominoes with 1 hole.at n=15A057423
• Composite and every divisor (except 1) contains the digit 4.at n=10A062670
• a(n) = 1 + 2 * least i such that A103507(i)=n+1, 0 if no such i exists.at n=30A103508
• Numbers whose Matula tree is a binary tree (i.e., root has degree 2 and all nodes except root and leaves have degree 3).at n=15A111299
• Distinct values of A218787 in the order of appearance.at n=19A218609
• a(n) = n*(21*n-17)/2.at n=43A226491
• Triangle read by rows: row n>=1 contains in increasing order the Matula numbers of the rooted binary trees with n leaves.at n=16A245824
• Matula-Goebel numbers of rooted trees in which all positive outdegrees are the same.at n=45A298424
• Number of nX2 0..1 arrays with every element unequal to 1, 2, 3 or 6 king-move adjacent elements, with upper left element zero.at n=11A304143
• Matula-Goebel numbers of unlabeled binary rooted semi-identity trees.at n=10A339193
• Matula-Goebel number of the rooted binary tree with Colijn-Plazzotta number n.at n=13A356121
• Semiprimes of the form k^2 + 5.at n=41A361696