A007951 Ternary sieve: delete every 3rd number, then every 9th, 27th, etc.

1, 2, 4, 5, 7, 8, 10, 11, 14, 16, 17, 19, 20, 22, 23, 25, 28, 29, 31, 32, 34, 35, 37, 38, 41, 43, 46, 47, 49, 50, 52, 55, 56, 58, 59, 61, 62, 64, 65, 68, 70, 71, 73, 74, 76, 77, 79, 82, 83, 85, 86, 88, 91, 92, 95, 97, 98, 100, 101, 103, 104, 106, 109, 110, 112, 113, 115, 116, 118

Offset: 1

Author

R. Muller

Keywords

• nonn

Comments

Smarandache calls this a "trinary" sieve. - N. J. A. Sloane, Jan 03 2020

The asymptotic density of this sequence is Product_{k>=1} (1 - 1/3^k) = 0.560126... (A100220). - Amiram Eldar, Mar 21 2021

Links

• Rémy Sigrist, Table of n, a(n) for n = 1..25000
• Florentin Smarandache, Only Problems, Not Solutions!, 4th ed., 1993; Problem 96.
• Index entries for sequences generated by sieves

Crossrefs

Cf. A007950, A092418, A100220.

Programs

PARI

v = List([1..118]); t=3; while (#v>=t, forstep (k=#v\t, 1, -1, listpop(v, k*t);); t*=3;); print (v) \\ Rémy Sigrist, Jan 05 2020