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!)
A275059 Numbers n such that A000010(n) + n^2 is a prime. 1
1, 2, 3, 5, 11, 13, 15, 19, 31, 33, 35, 41, 51, 53, 59, 65, 83, 89, 91, 101, 103, 115, 131, 141, 149, 161, 163, 181, 185, 187, 191, 193, 199, 217, 221, 233, 241, 263, 281, 287, 295, 303, 329, 331, 349, 373, 401, 415, 419, 431, 433, 445, 449, 461, 463, 469, 473, 499, 517 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

For n >= 2, a(n) is odd and squarefree. - Robert Israel, Jul 29 2016

LINKS

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

EXAMPLE

5 is a term because A000010(5) + 5^2 = 29 is a prime number.

MAPLE

select(t -> isprime(numtheory:-phi(t) + t^2), [1, 2, seq(n, n=3..1000, 2)]); # Robert Israel, Jul 29 2016

MATHEMATICA

Select[Range[2000], PrimeQ[#^2 + EulerPhi[#]] &]

PROG

(MAGMA) [n: n in [1..800] | IsPrime(n^2+EulerPhi(n))];

(PARI) isok(n) = isprime(eulerphi(n) + n^2); \\ Altug Alkan, Jul 27 2016

CROSSREFS

Cf. A000010, A259145.

Sequence in context: A269004 A100475 A187921 * A072538 A225856 A322173

Adjacent sequences:  A275056 A275057 A275058 * A275060 A275061 A275062

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Jul 27 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 July 24 17:43 EDT 2021. Contains 346273 sequences. (Running on oeis4.)