20212

Appears in sequences

• T(n,1) + T(n,2) + ... T(n,n), where T is the array in A026098.at n=30A026101
• Numbers n such that n through n+5 have the same number of distinct prime factors.at n=22A045934
• Numbers n such that n through n+6 are divisible by the same number of distinct primes.at n=9A045935
• Binary numbers with 2 replacing 1 in odd positions.at n=23A095914
• Ternary emirpimes.at n=15A119684
• Number of walks within N^2 (the first quadrant of Z^2) starting at (0,0) and consisting of n steps taken from {(-1, -1), (-1, 1), (0, 1), (1, -1)}.at n=11A151258
• Numbers k such that 9 + 10^k + 9*100^k is prime.at n=12A171227
• Number of convex quadrilaterals, distinct up to congruence, on an n X n grid (or geoboard).at n=8A181944
• Numbers 3*n + 2 written in base 3.at n=61A190642
• Put the natural numbers together without spaces and read them five at a time advancing one space each time.at n=29A193493
• a(n) = floor(volume of 4-sphere of radius n).at n=8A210519
• Numbers with digits in {0,1,2} such that every other digit is strictly less than its neighbors.at n=28A306105