18742

Appears in sequences

• Number of (binary) bit strings of length n having an even length block of 0's followed by an odd length block of 1's.at n=12A065506
• Numbers n such that h(n) = 3 h(n-1) where h(n) is the length of the sequence {n, f(n), f(f(n)), ...., 1} in the Collatz (or 3x + 1) problem. (The earliest "1" is meant.)at n=18A078420
• Let M(n) be the n X n matrix m(i,j)=min(i,j) for 1<=i,j<=n then a(n) is the trace of M(n)^(-6).at n=21A114358
• Indices of primes in the Padovan sequence A000931.at n=23A152870
• The number of decimal digits in the Lucas-Lehmer number A003010(n).at n=15A177874
• The number of decimal digits in Lucas-Lehmer numbers A003010(k-2) divisible by 2^k-1.at n=4A177875
• Number of (n+2)X(1+2) 0..3 arrays with every 3X3 subblock row and diagonal sum equal to 0 2 5 6 or 7 and every 3X3 column and antidiagonal sum not equal to 0 2 5 6 or 7.at n=9A252672
• Number of sets of exactly seven positive integers <= n having a square element sum.at n=17A281867
• Numbers k such that k!6 + 9 is prime, where k!6 is the sextuple factorial number (A085158 ).at n=31A288154