33170

Appears in sequences

• All 81 combinations of prefixing and following a(n) by a single digit are nonprime.at n=21A032734
• a(n) cannot be prefixed or followed by any digit to form a prime ('empty' prefixes allowed).at n=3A032736
• Composite numbers k such that all the decimal concatenations ik and ikj (i, j = 1...9) are also composite.at n=14A032737
• a(n) cannot be prefixed or followed by any digit to form a prime ('empty' prefixes and suffixes are allowed).at n=2A032738
• Indices k such that the (k+1)-st partial sum of primes divided by k is an integer.at n=13A134126
• Successive powers of two, represented as binary coded decimal. (0x1, 0x2, 0x4, 0x8, 0x16, 0x32, etc.)at n=13A158324
• The last n digits of powers of 2 start cycling. a(n) is the number of zero-free terms in this cycle.at n=6A181610
• Number of n X 3 binary arrays with some 1 horizontally or vertically adjacent to some other 1 exactly once.at n=6A268735
• Number of nX7 binary arrays with some 1 horizontally or vertically adjacent to some other 1 exactly once.at n=2A268739
• T(n,k)=Number of nXk binary arrays with some 1 horizontally or vertically adjacent to some other 1 exactly once.at n=38A268740
• T(n,k)=Number of nXk binary arrays with some 1 horizontally or vertically adjacent to some other 1 exactly once.at n=42A268740
• Numbers k such that (10^k + 101)/3 is prime.at n=29A271882
• Expansion of g.f. A(x) satisfying A(x) = A( x^2*(1+x)^5 ) / x.at n=8A369555