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!)
A238202 Primes p such that b = 2*p + 1 is semiprime and c = 2*b + 1 is 3-almost prime. 1
43, 503, 631, 827, 971, 1063, 1153, 1283, 1373, 1429, 1433, 1493, 1523, 1553, 1619, 1693, 1877, 2113, 2239, 2243, 2297, 2423, 2477, 2531, 2609, 2683, 2851, 2927, 2999, 3203, 3221, 3319, 3463, 3533, 3557, 3571, 3583, 3701 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Subsequence of A234095 and A000040, e.g., a(1) = 43 = A234095(4) = A000040(14).

LINKS

Table of n, a(n) for n=1..38.

EXAMPLE

2*43 + 1 = 87 = 2*29 = A001358(30), 2*87 + 1 = 175 = 5*5*7 = A014612(43).

PROG

(PARI) forprime(p=2, 4000, if(bigomega(a=2*p+1)==2&&bigomega(b=2*a+1)==3, print(p", ")))

CROSSREFS

Cf. A000040, A001358, A014612, A234095.

Sequence in context: A194784 A184153 A184145 * A008388 A241939 A251896

Adjacent sequences:  A238199 A238200 A238201 * A238203 A238204 A238205

KEYWORD

nonn

AUTHOR

Zak Seidov, Feb 20 2014

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 21 04:58 EDT 2020. Contains 337267 sequences. (Running on oeis4.)