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.

A228234 Number of strict Gaussian primes of norm less than or equal to n in the first quadrant on or below the first diagonal.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 7, 9, 10, 12, 15, 16, 18, 21, 22, 25, 29, 32, 35, 38, 42, 45, 47, 50, 55, 59, 62, 67, 71, 75, 79, 84, 88, 94, 99, 104, 108, 113, 117, 120, 127, 134, 137, 144, 149, 155, 160, 168, 176, 181, 185, 193, 202, 208, 213, 220, 227, 233, 241, 248, 256
Offset: 1

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Author

Olivier Gérard, Aug 17 2013

Keywords

Comments

Strict means that one does not include the ordinary integer primes and integer primes multiplied by i.
In the first quadrant and on or below the first diagonal, means here that the imaginary part is positive and inferior or equal to the real part.

Crossrefs

Cf. A211340 (number of strict Gaussian integers in this half-quadrant).
Cf. A228235 (a version of this sequence including the real axis).
Cf. A228232, A228233 (versions counting the whole first quadrant).

Programs

  • Mathematica
    nn = 100; t = Select[Flatten[Table[a + b*I, {a, nn}, {b, a, nn}]], PrimeQ[#, GaussianIntegers -> True] &]; t2 = Table[0, {nn}]; Do[f = Ceiling[Abs[i]]; If[f <= nn, t2[[f]]++], {i, t}]; Accumulate[t2] (* T. D. Noe, Aug 19 2013 *)

A228172 Number of integer pairs (x,y) such that 0<=y<=x, x>0, and x^2+y^2<=n^2.

Original entry on oeis.org

1, 3, 6, 9, 14, 19, 24, 31, 39, 48, 56, 65, 77, 88, 101, 113, 127, 141, 157, 174, 189, 208, 226, 244, 266, 287, 309, 330, 353, 378, 401, 428, 454, 482, 511, 537, 568, 596, 630, 662, 692, 726, 760, 797, 833, 867, 905, 942, 982, 1023, 1065, 1106, 1146, 1189, 1231, 1278, 1322, 1369, 1414, 1462, 1512
Offset: 1

Views

Author

Olivier Gérard, Aug 17 2013

Keywords

Comments

This corresponds to points of positive norm less than or equal to n on the square lattice, in the first quadrant, on or below the first diagonal.

Crossrefs

Cf. A211340 (version excluding the cases with y=0).

Formula

a(n) = A211340 (n) + n . [Joerg Arndt, Aug 19 2013]
Showing 1-2 of 2 results.