login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A281824 Numbers that are the sum of 6 consecutive semiprimes. 2
58, 75, 91, 107, 123, 142, 161, 175, 191, 205, 225, 241, 258, 278, 297, 316, 332, 348, 366, 385, 405, 429, 452, 473, 491, 508, 524, 536, 546, 566, 590, 614, 639, 664, 690, 706, 718, 732, 747, 762, 782, 802, 822, 838, 851, 872, 889, 906, 924, 945, 968, 990 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Semiprime analog of A127333. First terms that are also in A127333: 690, 990, 1172, 1250, 1286, 2288, 4798, 5064.

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

FORMULA

a(n) ~ 6n log n/log log n. - Charles R Greathouse IV, Jan 31 2017

MATHEMATICA

Total /@ Partition[Select[Range[4, 200], 2 == PrimeOmega[#] &], 6, 1]

PROG

(PARI) do(n)=my(v=List([58]), u=List(), t=58); forprime(p=2, n\2, forprime(q=2, min(p, n\p), listput(u, p*q))); u=Set(u); for(i=7, #u, listput(v, t+=u[i]-u[i-6])); Set(v) \\ Charles R Greathouse IV, Jan 31 2017

CROSSREFS

Cf. A001358, A127333.

Sequence in context: A127024 A010338 A184074 * A127334 A275702 A306115

Adjacent sequences:  A281821 A281822 A281823 * A281825 A281826 A281827

KEYWORD

nonn

AUTHOR

Zak Seidov, Jan 31 2017

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 October 15 04:33 EDT 2019. Contains 328026 sequences. (Running on oeis4.)