A109031 Numbers that have exactly eleven prime factors counted with multiplicity (A069272) whose digit reversal is different and also has 11 prime factors (with multiplicity).

295245, 426816, 542592, 618624, 2112480, 2116224, 2150064, 2154816, 2196000, 2302560, 2327616, 2342277, 2388672, 2555280, 2576896, 2599200, 2768832, 2952288, 2952576, 4017216, 4074240, 4074840, 4076160, 4076568, 4078848

Offset

1,1

Comments

This sequence is the k = 11 instance of the series which begins with k = 1 (emirps), k = 2, k = 3 (A109023), k = 4 (A109024), k = 5 (A109025), k = 6 (A109026), k = 7 (A109027), k = 8 (A109028), k = 9 (A109029), k = 10 (A109030).

Links

David A. Corneth, Table of n, a(n) for n = 1..10000

Eric Weisstein's World of Mathematics, Almost Prime.

Eric Weisstein's World of Mathematics, Emirp.

Eric Weisstein and Jonathan Vos Post, Emirpimes.

Example

a(1) = 295245 is in this sequence because 295245 = 3^10 * 5 has exactly 11 prime factors counted with multiplicity and reverse(295245) = 542592 = 2^7 * 3^3 * 157 also has 11 prime factors counted with multiplicity.

Prog

(PARI) is(n) = {
	my(r = fromdigits(Vecrev(digits(n))));
	n!=r && bigomega(n) == 11 && bigomega(r) == 11
} \\ David A. Corneth, Mar 07 2024

Crossrefs

Cf. A069272, A006567, A097393, A109018, A109023, A109024, A109025, A109026, A109027, A109028, A109029, A109030.

Sequence in context: A258534 A258527 A254919 * A137817 A137818 A303357

Adjacent sequences: A109028 A109029 A109030 * A109032 A109033 A109034

Keyword

nonn,base

Author

Jonathan Vos Post, Jun 16 2005

Extensions

a(5)-a(25) from Donovan Johnson, Apr 09 2010

Status

approved