cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-4 of 4 results.

A184935 Primes of the form k^2 + prime(k).

Original entry on oeis.org

3, 7, 23, 83, 181, 239, 563, 1013, 1447, 1607, 2129, 2729, 3167, 3881, 4673, 5849, 6481, 7489, 8563, 9719, 11813, 18713, 21563, 25247, 27197, 29221, 33469, 36467, 47977, 50683, 51599, 56237, 69257, 71389, 75731, 96893, 107119, 115163
Offset: 1

Views

Author

Jonathan Vos Post, Feb 02 2011

Keywords

Comments

Primes in A004232. Sequence A064711 has the values of k.

Examples

			3167 is here because 54^2 + prime(54) = 54^2 + 251 = 3167, which is prime.
		

Crossrefs

Programs

  • Magma
    [ a: k in [0..10000] | IsPrime(a) where a is k^2 + NthPrime(k) ]; // Vincenzo Librandi, Apr 14 2011
  • Mathematica
    Select[Table[k^2 + Prime[k], {k, 1000}], PrimeQ] (* Harvey P. Dale, Feb 16 2011 *)

Extensions

Better name from Zak Seidov, Apr 12 2011

A064711 Numbers n such that n^2 + prime(n) is a prime.

Original entry on oeis.org

1, 2, 4, 8, 12, 14, 22, 30, 36, 38, 44, 50, 54, 60, 66, 74, 78, 84, 90, 96, 106, 134, 144, 156, 162, 168, 180, 188, 216, 222, 224, 234, 260, 264, 272, 308, 324, 336, 344, 366, 368, 374, 378, 390, 402, 406, 422, 466, 468, 476, 492, 498, 502, 516, 604, 624, 636
Offset: 1

Views

Author

Robert G. Wilson v, Oct 13 2001

Keywords

Examples

			2 is in the sequence because 2^2 + Prime(2) = 4 + 3 = 7 is a prime.
		

Crossrefs

Programs

  • Magma
    [ n: n in [1..700] | IsPrime(n^2+NthPrime(n)) ]; // Klaus Brockhaus, Apr 12 2011
  • Mathematica
    Select[ Range[ 1000 ], PrimeQ[ #^2 + Prime[ # ] ] & ]
  • PARI
    { n=0; for (m=1, 10^9, if (isprime(m^2 + prime(m)), write("b064711.txt", n++, " ", m); if (n==1000, break)) ) } \\ Harry J. Smith, Sep 23 2009
    

A188831 Primes of the form k^2 - prime(k).

Original entry on oeis.org

23, 71, 107, 263, 487, 677, 787, 1427, 1583, 2081, 3319, 5393, 8713, 10247, 11071, 12377, 18257, 20477, 24659, 26573, 29243, 29927, 33487, 34949, 37223, 37991, 41981, 51449, 60917, 64937, 66977, 71167, 83357, 85667, 99013, 100271, 109313, 110629, 118757
Offset: 1

Views

Author

Zak Seidov, Apr 11 2011

Keywords

Comments

Or, primes in A073497. Corresponding values of k in A064712.
This is to A073497 and A064712 as A184935 is to A004232 and A064711.
The two primes prime(k) and k^2-prime(k) are a Goldbach partition of k^2. - T. D. Noe, Apr 14 2011

Examples

			23 is here because 6^2 - prime(6) = 36 - 13 = 23.
		

Crossrefs

Programs

  • Magma
    [ a: k in [0..10000] | IsPrime(a) where a is k^2-NthPrime(k) ]; // Vincenzo Librandi, Apr 14 2011
  • Mathematica
    Select[Table[k^2 - Prime[k], {k, 1000}], PrimeQ] (* T. D. Noe, Apr 14 2011 *)

Formula

a(n) = A073497(A064712(n)).

A356868 a(n) = n^2 * prime(n).

Original entry on oeis.org

2, 12, 45, 112, 275, 468, 833, 1216, 1863, 2900, 3751, 5328, 6929, 8428, 10575, 13568, 17051, 19764, 24187, 28400, 32193, 38236, 43907, 51264, 60625, 68276, 75087, 83888, 91669, 101700, 122047, 134144, 149193, 160684, 182525, 195696, 214933, 235372, 254007, 276800, 300899
Offset: 1

Views

Author

Alex Ratushnyak, Sep 01 2022

Keywords

Crossrefs

Programs

  • Mathematica
    a[n_] := n^2 * Prime[n]; Array[a, 40] (* Amiram Eldar, Sep 02 2022 *)
  • Python
    from sympy import prime
    def a(n): return n**2 * prime(n)
    print([a(n) for n in range(1, 41)]) # Michael S. Branicky, Sep 01 2022
Showing 1-4 of 4 results.