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 1-2 of 2 results.

A292578 Primes of the form 11*n^2 + 55*n + 43.

Original entry on oeis.org

43, 109, 197, 307, 439, 593, 769, 967, 1187, 1429, 1693, 1979, 2287, 2617, 2969, 3343, 3739, 4157, 4597, 5059, 6577, 7127, 7699, 8293, 9547, 10889, 11593, 14629, 15443, 17137, 18919, 19843, 20789, 21757, 24793, 25849, 26927, 28027, 30293, 32647, 33857, 35089
Offset: 1

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Author

Waldemar Puszkarz, Sep 19 2017

Keywords

Comments

The first 20 terms correspond to n from 0 to 19, which makes 11*n^2 + 55*n + 43 a prime-generating polynomial (see the link).
There are only a few prime-generating quadratic polynomials whose coefficients contain at most two digits that produce 20 or more primes in a row. This is one of them, others include A005846, A007641, A060844, and A007637.

Crossrefs

Cf. A000040, A005846, A007641, A060844, A007637 (similar sequences).

Programs

  • Maple
    select(isprime, [seq(11*n^2+55*n+43,n=0..100)]); # Robert Israel, Oct 01 2017
  • Mathematica
    Select[Range[0,100]//11#^2+55#+43 &, PrimeQ]
  • PARI
    for(n=0, 100, isprime(p=11*n^2+55*n+43)&& print1(p ", "))

A268101 Smallest prime p such that some polynomial of the form a*x^2 - b*x + p generates distinct primes in absolute value for x = 1 to n, where 0 < a < p and 0 <= b < p.

Original entry on oeis.org

2, 3, 5, 5, 7, 7, 11, 11, 11, 11, 13, 13, 17, 17, 17, 17, 19, 19, 23, 23, 23, 23, 29, 29, 29, 29, 29, 29, 31, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 647, 1277, 1979, 2753
Offset: 1

Views

Author

Arkadiusz Wesolowski, Jan 26 2016

Keywords

Examples

			a(1) = 2 (a prime), x^2 + 2 gives a prime for x = 1.
a(2) = 3 (a prime), 2*x^2 + 3 gives distinct primes for x = 1 to 2.
a(4) = 5 (a prime), 2*x^2 + 5 gives distinct primes for x = 1 to 4.
a(6) = 7 (a prime), 4*x^2 + 7 gives distinct primes for x = 1 to 6.
a(10) = 11 (a prime), 2*x^2 + 11 gives distinct primes for x = 1 to 10.
a(12) = 13 (a prime), 6*x^2 + 13 gives distinct primes for x = 1 to 12.
a(16) = 17 (a prime), 6*x^2 + 17 gives distinct primes for x = 1 to 16.
a(18) = 19 (a prime), 10*x^2 + 19 gives distinct primes for x = 1 to 18.
a(22) = 23 (a prime), 3*x^2 - 3*x + 23 gives distinct primes for x = 1 to 22.
a(28) = 29 (a prime), 2*x^2 + 29 gives distinct primes for x = 1 to 28.
a(29) = 31 (a prime), 2*x^2 - 4*x + 31 gives distinct primes for x = 1 to 29.
a(40) = 41 (a prime), x^2 - x + 41 gives distinct primes for x = 1 to 40.
a(41) = 647 (a prime), abs(36*x^2 - 594*x + 647) gives distinct primes for x = 1 to 41.
a(42) = 1277 (a prime), abs(36*x^2 - 666*x + 1277) gives distinct primes for x = 1 to 42.
a(43) = 1979 (a prime), abs(36*x^2 - 738*x + 1979) gives distinct primes for x = 1 to 43.
a(44) = 2753 (a prime), abs(36*x^2 - 810*x + 2753) gives distinct primes for x = 1 to 44.
		

Crossrefs

Showing 1-2 of 2 results.