A076963 Lexicographically earliest increasing sequence of relatively prime numbers with nondecreasing number of divisors. a(1) = 1, tau(a(n+1)) >= tau(a(n)) and GCD(a(n),a(n+1)) = 1.

1, 2, 3, 4, 9, 10, 21, 22, 27, 28, 45, 52, 63, 64, 105, 128, 135, 136, 165, 182, 225, 256, 315, 352, 525, 544, 585, 608, 675, 704, 945, 1144, 1575, 2288, 2835, 2992, 4095, 5984, 5985, 7072, 7245, 7904, 8085, 9568, 9765, 10208, 11025, 11968, 12285, 23936, 25935

Offset

0,2

Comments

It appears that a(n) is divisible by 2 iff n is odd, and by 3 iff n >= 2 is even. - Robert Israel, Jun 08 2024

Links

Robert Israel, Table of n, a(n) for n = 0..200

Maple

R:= 1: d:= 1: count:= 1: x:= 1:
for i from 2 while count < 80 do
  if igcd(i, x) = 1 then
    di:= numtheory:-tau(i);
    if di >= d then x:= i; d:= di; R:= R, i; count:= count+1 fi
  fi
od:
R; # Robert Israel, Jun 07 2024

Crossrefs

Sequence in context: A127150 A256189 A098548 * A081871 A366913 A329573

Adjacent sequences: A076960 A076961 A076962 * A076964 A076965 A076966

Keyword

nonn

Author

Amarnath Murthy, Oct 21 2002

Extensions

More terms from Sascha Kurz, Jan 22 2003

Definition clarified by Robert Israel, Jun 07 2024

Status

approved