login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A061368 Lesser of twin primes (p, p+2) whose average p+1 is not squarefree. 1
3, 11, 17, 59, 71, 107, 149, 179, 191, 197, 227, 239, 269, 311, 347, 419, 431, 521, 599, 659, 809, 827, 881, 1019, 1031, 1049, 1061, 1091, 1151, 1277, 1319, 1427, 1451, 1487, 1607, 1619, 1667, 1787, 1871, 1931, 1949, 1997, 2027, 2087, 2111, 2141, 2267 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1000 from Harry J. Smith)

FORMULA

Intersection of A014574 and A013929.

MATHEMATICA

Select[Select[Partition[Prime[Range[400]], 2, 1], #[[2]]-#[[1]]==2&][[All, 1]], !SquareFreeQ[#+1]&] (* Harvey P. Dale, Oct 21 2016 *)

PROG

(PARI) { n=-1; forprime (p=2, 119099, if (isprime(p+2) && !issquarefree(p+1), write("b061368.txt", n++, " ", p)) ) } \\ Harry J. Smith, Jul 22 2009

(MAGMA) [p:p in PrimesUpTo(2500)| IsPrime(p+2) and not IsSquarefree(p+1)]; // Marius A. Burtea, Jan 16 2020

CROSSREFS

Cf. A001359, A005117, A014574, A013929.

Sequence in context: A245045 A127996 A032008 * A145701 A072982 A124787

Adjacent sequences:  A061365 A061366 A061367 * A061369 A061370 A061371

KEYWORD

nonn,changed

AUTHOR

Labos Elemer, Jun 07 2001

EXTENSIONS

Offset corrected by Amiram Eldar, Jan 16 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 January 22 04:27 EST 2020. Contains 331133 sequences. (Running on oeis4.)