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!)
A175463 Numbers k such that 8*k + 5 is semiprime. 1
2, 8, 9, 10, 11, 16, 17, 25, 26, 27, 29, 31, 37, 38, 42, 45, 47, 51, 54, 55, 56, 58, 60, 61, 62, 64, 66, 70, 71, 72, 73, 74, 78, 83, 85, 89, 93, 97, 98, 101, 108, 111, 112, 114, 116, 118, 120, 121, 123, 129, 134, 137, 141, 142, 143, 144, 145, 148, 150, 156, 157, 160 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..62.

FORMULA

a(n) = (A175461(n) - 5)/8.

MATHEMATICA

Select[Range[200], PrimeOmega[8#+5]==2&] (* Harvey P. Dale, Aug 07 2011 *)

PROG

(MAGMA) IsSemiprime:=func< n | &+[ k[2]: k in Factorization(n) ] eq 2 >; [ n: n in [2..200] | IsSemiprime(8*n+5) ]; // Vincenzo Librandi, Dec 13 2010

CROSSREFS

Cf. A175461 Semiprimes of form 8*n+5.

Sequence in context: A247635 A152754 A001560 * A167450 A050569 A318175

Adjacent sequences:  A175460 A175461 A175462 * A175464 A175465 A175466

KEYWORD

nonn

AUTHOR

Zak Seidov, May 24 2010

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 April 6 13:53 EDT 2020. Contains 333276 sequences. (Running on oeis4.)