The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A032720 Integers that when prefixed by '3' and followed by '7' yield a prime. 0
0, 1, 3, 4, 6, 9, 13, 16, 18, 21, 25, 30, 34, 40, 45, 46, 51, 52, 54, 55, 60, 61, 63, 67, 69, 72, 76, 79, 84, 87, 90, 91, 94, 96, 114, 117, 123, 124, 126, 127, 130, 132, 133, 135, 138, 139, 147, 151, 154, 156, 160, 162, 165, 166, 168, 172, 181, 184, 190, 195 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
LINKS
MAPLE
q:= k-> isprime(parse(""||3||k||7)):
select(q, [$0..200])[]; # Alois P. Heinz, Jul 16 2022
MATHEMATICA
Select[Range[0, 250], PrimeQ[FromDigits[Join[{3}, IntegerDigits[#], {7}]]]&] (* Harvey P. Dale, Dec 19 2010 *)
PROG
(PARI) isok(k) = isprime(eval(concat(3, concat(Str(k), 7)))); \\ Michel Marcus, Jul 16 2022
CROSSREFS
Sequence in context: A140570 A285303 A135072 * A289117 A355697 A167928
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, May 15 1998
EXTENSIONS
Name edited and offset 1 from Michel Marcus, Jul 16 2022
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 28 12:54 EDT 2024. Contains 372913 sequences. (Running on oeis4.)