211213

Properties

Appears in sequences

• Summarize the previous term (digits in increasing order), starting with a(1) = 1.at n=5A005151
• Look and Say sequence: describe the previous term! (method C - initial term is 2).at n=4A023989
• Primes that are concatenations of n with n + 2.at n=23A032625
• Summarize the previous term in base 4 (in increasing order).at n=5A098155
• Number of n X 2 (-1,0,1) arrays of determinants of 2 X 2 subblocks of some (n+1) X 3 binary array with rows and columns of the latter in lexicographically nondecreasing order.at n=23A226866
• a(n) = A047842(A047842(n)), say what you see, once repeated.at n=23A235775
• a(n) = A047842(A047842(n)), say what you see, once repeated.at n=32A235775
• Primes formed from the concatenation of previousprime(n) and n.at n=19A280576
• Prime numbersat n=18909