19769

Appears in sequences

• Numbers k such that the continued fraction for sqrt(k) has period 69.at n=17A020408
• Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted the two central terms are both 21.at n=7A031609
• Column k=4 sequence of array A103728.at n=7A103731
• Number of n X 3 binary arrays with row sums nondecreasing and columns lexicographically nondecreasing.at n=7A267240
• T(n,k)=Number of nXk binary arrays with row sums nondecreasing and columns lexicographically nondecreasing.at n=52A267245
• Breadth-first reading of the subtree rooted at 7 of the tree where each parent node is the arithmetic derivative (A003415) of all its children.at n=32A327977
• a(n) = numerator(Sum_{k=1..n} d(k+1)/d(k)), where d is the number of divisors function.at n=39A386925