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!)
A188673 a(n) = smallest semiprime such that prime(n) = a(n) - p, p prime. 1
4, 6, 10, 9, 14, 15, 22, 21, 25, 34, 33, 39, 46, 46, 49, 55, 62, 74, 69, 74, 86, 82, 85, 91, 134, 106, 106, 118, 111, 115, 129, 133, 142, 141, 166, 158, 159, 166, 169, 178, 202, 183, 194, 206, 202, 201, 213, 226, 274, 302, 235, 262, 254, 253, 259, 265, 274, 274, 314, 298, 302 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..61.

EXAMPLE

a(1) =  4 because prime(1) =  4 - 2;

a(2) =  6 because prime(2) =  6 - 3;

a(3) = 10 because prime(3) = 10 - 5;

a(4) =  9 because prime(4) =  9 - 2;

a(5) = 14 because prime(5) = 14 - 3.

MAPLE

isA001358 := proc(n) return(numtheory[bigomega](n) = 2) ; end proc:

A188673 := proc(n) local p, j ; p := ithprime(n) ; for j from 1 do if isA001358(p+ithprime(j)) then return p+ithprime(j) ; end if; end do; end proc: # R. J. Mathar, Apr 16 2011

CROSSREFS

Cf. A000040, A001358.

Sequence in context: A249982 A292767 A117622 * A193951 A129854 A088682

Adjacent sequences:  A188670 A188671 A188672 * A188674 A188675 A188676

KEYWORD

nonn

AUTHOR

Michel Lagneau, Apr 14 2011

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 September 23 16:41 EDT 2020. Contains 337315 sequences. (Running on oeis4.)