login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A083372 Least number having exactly two odd prime factors that differ by 2n. 0
15, 21, 55, 33, 39, 85, 51, 57, 115, 69, 203, 145, 87, 93, 259, 185, 111, 205, 123, 129, 235, 141, 371, 265, 159, 413, 295, 177, 183, 469, 335, 201, 355, 213, 219, 553, 395, 237, 415, 249, 623, 445, 267, 1313, 679, 485, 291, 505, 303, 309, 535, 321, 327, 565 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The lesser of the two factors is in A002373.

LINKS

Table of n, a(n) for n=1..54.

EXAMPLE

We have a(4) = 33 because 33 = 3*11, with 11 - 3 = 2*4, the smallest number with this property. Others are 85 = 5*13, 209 = 11*19, 713 = 23*31, 1073 = 29*37, 3233 = 53*61, ...

MATHEMATICA

f[n_] := Block[{p = 3}, While[ ! PrimeQ[p] || ! PrimeQ[p + 2n], p++ ]; p(p + 2n)]; Table[ f[n], {n, 1, 55}]

Table[#(#+2n)&/@Select[Prime[Range[2, 100]], PrimeQ[#+2n]&, 1], {n, 60}]// Flatten (* Harvey P. Dale, May 26 2018 *)

CROSSREFS

Cf. A046388.

Sequence in context: A015831 A275169 A063176 * A119101 A190662 A274084

Adjacent sequences:  A083369 A083370 A083371 * A083373 A083374 A083375

KEYWORD

nonn

AUTHOR

Lekraj Beedassy, Jun 05 2003

EXTENSIONS

Edited and extended by Robert G. Wilson v, Jun 07 2003

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 November 15 18:59 EST 2019. Contains 329149 sequences. (Running on oeis4.)