login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A046442 Semiprimes whose two prime factors are distinct in length. 1
22, 26, 33, 34, 38, 39, 46, 51, 55, 57, 58, 62, 65, 69, 74, 77, 82, 85, 86, 87, 91, 93, 94, 95, 106, 111, 115, 118, 119, 122, 123, 129, 133, 134, 141, 142, 145, 146, 155, 158, 159, 161, 166, 177, 178, 183, 185, 194, 201, 202, 203, 205, 206, 213, 214, 215, 217 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..57.

EXAMPLE

203 because 203 = 7 * 29, which have 1 and 2 digits, respectively.

MATHEMATICA

Take[Union[Times@@@Select[Subsets[Prime[Range[50]], {2}], IntegerLength[#[[1]]]!=IntegerLength[#[[2]]]&]], 60] (* Harvey P. Dale, Dec 29 2010 *)

CROSSREFS

Cf. A001358 (semiprimes).

Sequence in context: A084891 A162422 A063940 * A101549 A277624 A243140

Adjacent sequences:  A046439 A046440 A046441 * A046443 A046444 A046445

KEYWORD

nonn,base

AUTHOR

Patrick De Geest, Jul 15 1998

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 19 12:41 EDT 2021. Contains 345129 sequences. (Running on oeis4.)