A356850 a(1) = 1, a(2) = 2; for n > 2, a(n) is the smallest positive number not occurring earlier such that a(n) is coprime to the previous Omega(a(n)) terms.
1, 2, 3, 5, 4, 7, 9, 10, 11, 13, 6, 17, 19, 14, 15, 23, 22, 21, 25, 26, 29, 27, 31, 8, 33, 35, 34, 37, 39, 38, 41, 43, 45, 28, 47, 51, 46, 49, 53, 55, 12, 59, 61, 57, 20, 67, 69, 58, 65, 71, 62, 63, 73, 74, 77, 75, 79, 52, 83, 85, 81, 44, 89, 87, 82, 91, 93, 86, 95, 97, 94, 99, 101, 103, 50, 107
Offset: 1
Keywords
Examples
a(7) = 9 as Omega(9) = A001222(9) = 2, and 9 is coprime to the previous two terms, namely a(6) = 7 and a(5) = 4.
Links
- Michael De Vlieger, Table of n, a(n) for n = 1..16384
- Michael De Vlieger, Annotated log-log scatterplot of a(n) n = 1..2^15, showing records in red, local minima in blue, highlighting primes in green, other prime powers in gold, and numbers neither prime powers nor squarefree in light blue.
- Michael De Vlieger, Annotated log-log scatterplot of a(n) n = 1..2^15, highlighting composite prime powers. Aside from composite 2^e, p^e appears early.
- Michael De Vlieger, Log log scatterplot of a(n), n = 1..2^15, with a color function according to Omega(a(n)), where red = 1, amber = 2, ..., dark blue = 6.
- Scott R. Shannon, Image for n=1..100000. The green line is y = n.
- Scott R. Shannon, Image for n=1..100000 with color. Terms with lowest prime factor of 2 are show in red, those with 3 in yellow, those with 5 in green, and all others in white.
- Scott R. Shannon, Image for n=1..1000000.
- Scott R. Shannon, Image for n=1..1000000 with color. The terms 24 and 36 can be seen on the x-axis at the bottom right in red.
Comments