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!)
A112774 Semiprimes of the form 6n+4. 10
4, 10, 22, 34, 46, 58, 82, 94, 106, 118, 142, 166, 178, 202, 214, 226, 262, 274, 298, 334, 346, 358, 382, 394, 454, 466, 478, 502, 514, 526, 538, 562, 586, 622, 634, 694, 706, 718, 766, 778, 802, 838, 862, 886, 898, 922, 934, 958, 982, 1006, 1018, 1042, 1114 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

{6} + A112772 + A112774 = A100484 = 2*A000040.

Conjecture: A232324(a(n)) = 1 for n > 2, where A232324(m) = antisigma(m) mod sigma(m) = A024816(m) mod A000203(m). - Jaroslav Krizek, Nov 27 2013

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

FORMULA

a(n) = 2 * A003627(n) = 6 * A024893(n) + 4.

MATHEMATICA

Select[6 Range[0, 200] + 4, PrimeOmega[#] == 2&] (* Vincenzo Librandi, Sep 22 2012 *)

PROG

(MAGMA) IsSemiprime:=func<n | &+[d[2]: d in Factorization(n)] eq 2>; [s: n in [0..200] | IsSemiprime(s) where s is 6*n + 4]; // Vincenzo Librandi, Sep 22 2012

CROSSREFS

Sequence in context: A217514 A235142 A250398 * A227225 A008178 A009891

Adjacent sequences:  A112771 A112772 A112773 * A112775 A112776 A112777

KEYWORD

easy,nonn

AUTHOR

Jonathan Vos Post and Ray Chandler, Oct 15 2005

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 January 29 16:58 EST 2020. Contains 331347 sequences. (Running on oeis4.)