A290020 Sort the positive integers according to 3 keys, which are, in order of priority, number of digits, Omega (A001222), and the number itself.

1, 2, 3, 5, 7, 4, 6, 9, 8, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 10, 14, 15, 21, 22, 25, 26, 33, 34, 35, 38, 39, 46, 49, 51, 55, 57, 58, 62, 65, 69, 74, 77, 82, 85, 86, 87, 91, 93, 94, 95, 12, 18, 20, 27, 28, 30, 42, 44

Offset

1,2

Links

Ivan Neretin, Table of n, a(n) for n = 1..9999

Index entries for sequences that are permutations of the natural numbers

Mathematica

Table[SortBy[Range[10^(n - 1), 10^n - 1], PrimeOmega], {n, 2}] // Flatten (* Michael De Vlieger, Jul 20 2017 *)

Prog

(PARI) upto(t10nm1) = {my(v, res = []); for(i=1, t10nm1, res = concat(res, vecsort(vector(9*10^(i-1), j, k=j+10^(i-1)-1; [bigomega(k), k])))); vector(#res, i, res[i][2])}
(PARI) mycmp(x, y) = my(dd = #digits(x) - #digits(y)); if (dd, sign(dd), sign(bigomega(x) - bigomega(y)));
lista(nn) = {v = vector(10^#Str(nn), k, k); w = vecsort(v, mycmp); vector(nn, k, w[k]); } \\ Michel Marcus, Jul 21 2017

Crossrefs

Cf. A001222, A055642, A290019.

Sequence in context: A075241 A239694 A097883 * A178595 A098284 A082196

Adjacent sequences: A290017 A290018 A290019 * A290021 A290022 A290023

Keyword

nonn,base,easy

Author

David A. Corneth, Jul 19 2017

Extensions

Definition clarified by Giovanni Resta, Jul 27 2017

Status

approved