21342

Appears in sequences

• McKay-Thompson series of class 45b for Monster.at n=59A058686
• Numbers which are the sum of their proper divisors containing the digit 7.at n=25A059466
• Number of ways to toss a coin n times and not get a run of five.at n=15A135492
• Partial sums of economical numbers A046759.at n=20A172460
• Ulam numbers k such that 4*k and 16*k are also Ulam numbers.at n=31A287634
• Number of function calls of the first kind required to compute ack(3,n), where ack denotes the Ackermann function.at n=5A304370
• a(n) is the number of optimal strategies for Player I in the Penney-Ante game with strings of length n.at n=16A344903
• a(n) = Sum_{j=1..n} Sum_{k=1..n} tau(j*k).at n=41A372674