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.

A362979 Square array, read by descending antidiagonals: row n lists the primes whose base-2 representation has exactly n ones, starting from n=3.

Original entry on oeis.org

7, 11, 23, 13, 29, 31, 19, 43, 47, 311
Offset: 3

Views

Author

Clark Kimberling, May 11 2023

Keywords

Examples

			Corner:
  n=3:    7    11    13    19    37   41     67    73    97
  n=4:   23    29    43    53    71   83     89   101   113
  n=5:   31    47    59    61    79   103   107   109   151
  n=6:  311   317   347   349   359   373   461   467   571
The first four primes in row n=3 have these base-2 representations, respectively: 111, 1011, 1101, 10011.
		

Crossrefs

Cf. A019434 (row 2), A061712 (column 1), A081091 (row 3), A095077 (row 4).

Programs

  • Mathematica
    t[n_] := Count[IntegerDigits[Prime[n], 2], 1]  (* A014499 *)
    u = Table[t[n], {n, 1, 200}];
    p[n_] := Flatten[Position[u, n]]
    w = TableForm[Table[Prime[p[n]], {n, 3, 16}]]

Extensions

New offset and edited by Michel Marcus, Jan 19 2024