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 1-3 of 3 results.

A219606 Prime gaps and primes interleaved.

Original entry on oeis.org

1, 2, 2, 3, 2, 5, 4, 7, 2, 11, 4, 13, 2, 17, 4, 19, 6, 23, 2, 29, 6, 31, 4, 37, 2, 41, 4, 43, 6, 47, 6, 53, 2, 59, 6, 61, 4, 67, 2, 71, 6, 73, 4, 79, 6, 83, 8, 89, 4, 97, 2, 101, 4, 103, 2, 107, 4, 109, 14, 113, 4, 127, 6, 131, 2, 137, 10, 139, 2, 149, 6
Offset: 1

Views

Author

Reinhard Zumkeller, Dec 12 2012

Keywords

Crossrefs

Cf. A134735.

Programs

  • Haskell
    import Data.List (transpose)
    a219606 n = a219606_list !! (n-1)
    a219606_list = concat $ transpose [a001223_list, a000040_list]

A224888 Primes of the form p^2 + (q-p)^2, where p and q are consecutive primes.

Original entry on oeis.org

5, 13, 29, 293, 997, 6257, 11897, 18773, 19421, 52457, 73477, 109597, 120413, 167381, 192737, 218233, 249017, 292717, 333029, 361237, 398261, 466553, 502781, 546137, 552113, 591377, 635353, 683933, 687341, 704117, 737897, 885517, 966353, 982117, 1018097, 1079621
Offset: 1

Views

Author

Thomas Ordowski, Jul 24 2013

Keywords

Comments

Primes of the form A000040(n)^2 + A001223(n)^2.
Primes of the form A134735(2n-1)^2 + A134735(2n)^2.
Conjecture: a(n) ~ A093343(n).
There are 20421247 members of this sequence below 10^20. - Charles R Greathouse IV, Jul 29 2013

Examples

			3 and 5 are consecutive primes and 3^2 + (5-3)^2 = 9 + 4 = 13 is prime, so 13 is in the sequence.
		

Crossrefs

Cf. A093343.

Programs

  • Mathematica
    Select[Table[Prime[n]^2 + (Prime[n + 1] - Prime[n])^2, {n, 200}], PrimeQ] (* Alonso del Arte, Jul 29 2013 *)
  • PARI
    p=2;forprime(q=3,1e4,if(isprime(t=p^2+(q-p)^2),print1(t", "));p=q) \\ Charles R Greathouse IV, Jul 24 2013

Formula

c(x) is O( sqrt(x/log x) / log x ), where c(x) is the counting function, the number of terms less than x.

Extensions

a(5), a(9)-a(36) from Charles R Greathouse IV, Jul 24 2013

A340202 Primes followed by the difference from the next prime calculated by adding the digits of the lexicographically earliest distinct term.

Original entry on oeis.org

2, 1, 3, 20, 5, 110, 7, 4, 11, 200, 13, 22, 17, 1001, 19, 40, 23, 6, 29, 1010, 31, 15, 37, 112, 41, 1100, 43, 121, 47, 24, 53, 33, 59, 2000, 61, 42, 67, 130, 71, 10001, 73, 51, 79, 202, 83, 60, 89, 8, 97, 220, 101, 10010, 103, 301, 107, 10100, 109, 310, 113
Offset: 1

Views

Author

Carole Dubois, Dec 31 2020

Keywords

Examples

			Prime 2 + (1) = prime 3;
prime 3 + (2+0) = prime 5;
prime 5 + (1+1+0) = prime 7;
prime 7 + (4) = prime 11;
prime 11 + (2+0+0) = prime 13;
prime 13 + (2+2) = 17; etc.
		

Crossrefs

Cf. A000040 (primes), A219606.
Differences between consecutive primes: A001223, A134735, A340063.
Showing 1-3 of 3 results.