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!)
A334141 Numbers that are the product of distinct twin primes. 1
1, 3, 5, 7, 11, 13, 15, 17, 19, 21, 29, 31, 33, 35, 39, 41, 43, 51, 55, 57, 59, 61, 65, 71, 73, 77, 85, 87, 91, 93, 95, 101, 103, 105, 107, 109, 119, 123, 129, 133, 137, 139, 143, 145, 149, 151, 155, 165, 177, 179, 181, 183, 187, 191, 193, 195, 197, 199 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

Eric Weisstein's World of Mathematics, Twin Primes

MAPLE

N:= 1000: # for terms <= N

P:= select(isprime, {seq(i, i=3..N+2, 2)}):

TP:= P intersect map(`+`, P, 2):

TP:= map(t -> (t-2, t), TP):

TP:= sort(convert(TP, list)):

S:= {1}:

for i from 1 to nops(TP) do

  S0:= S;

  S:= S union map(`*`, select(`<=`, S, N/TP[i]), TP[i]);

od:

sort(convert(S, list)); # Robert Israel, Oct 28 2020

CROSSREFS

Subsequence of A005117.

Cf. A001097, A037074, A048599, A074480, A073485.

Sequence in context: A056911 A152955 A235866 * A325570 A210719 A322840

Adjacent sequences:  A334138 A334139 A334140 * A334142 A334143 A334144

KEYWORD

nonn

AUTHOR

Ilya Gutkovskiy, Apr 15 2020

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 June 12 14:20 EDT 2021. Contains 344956 sequences. (Running on oeis4.)