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!)
A275023 Cubes c such that c + 2 and c - 2 are semiprime. 1
8, 216, 1331, 2197, 4913, 9261, 15625, 35937, 59319, 68921, 117649, 185193, 421875, 531441, 658503, 704969, 1030301, 1367631, 3723875, 5268024, 5359375, 11390625, 13651919, 16581375, 17779581, 19902511, 23149125, 25672375, 29503629, 36264691, 38958219, 40353607 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Intersection of A000578 and A105571.

LINKS

K. D. Bajpai, Table of n, a(n) for n = 1..10000

EXAMPLE

a(1) = 8 = 2^3. Also, 8 + 2 = 10 = 2*5; 8 - 2 = 6 = 2*3; both are semiprime.

a(2) = 216 = 6^3. Also, 216 + 2 = 218 = 2*109; 216 - 2 = 214 = 2*107; both are semiprime.

MATHEMATICA

Select[Table[n^3, {n, 1000}], PrimeOmega[# + 2] == 2 && PrimeOmega[# - 2] == 2 &]

PROG

(PARI) for (n = 1, 1000, s = n^3; if(bigomega (s+2) == 2 && bigomega (s-2) == 2, print1 (s, ", ")))

CROSSREFS

Cf. A000578, A001358, A105571, A278022.

Sequence in context: A072159 A016827 A239222 * A163289 A060459 A007409

Adjacent sequences:  A275020 A275021 A275022 * A275024 A275025 A275026

KEYWORD

nonn

AUTHOR

K. D. Bajpai, Nov 12 2016

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 27 08:31 EST 2020. Contains 331293 sequences. (Running on oeis4.)