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.

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A354836 Triangle T(n,k) where, if n-k and n+k are prime, T(n,k) = n+k is the greater term of a Goldbach partition of 2n into two odd primes, or zero otherwise.

Original entry on oeis.org

3, 0, 5, 5, 0, 7, 0, 7, 0, 0, 7, 0, 0, 0, 11, 0, 0, 0, 11, 0, 13, 0, 0, 11, 0, 13, 0, 0, 0, 0, 0, 13, 0, 0, 0, 17, 11, 0, 0, 0, 0, 0, 17, 0, 19, 0, 13, 0, 0, 0, 17, 0, 19, 0, 0, 13, 0, 0, 0, 0, 0, 19, 0, 0, 0, 23, 0, 0, 0, 17, 0, 0, 0, 0, 0, 23, 0, 0, 0, 0, 17, 0, 19, 0, 0, 0, 23, 0, 0, 0, 0
Offset: 3

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Author

Jean-François Alcover, Jun 12 2022

Keywords

Comments

This sequence has the same structure as A354805, which could be considered as sort of its characteristic function.

Examples

			Triangle begins:
    3;
    0, 5;
    5, 0, 7;
    0, 7, 0, 0;
    7, 0, 0, 0,11;
    0, 0, 0,11, 0,13;
    0, 0,11, 0,13, 0, 0;
    0, 0, 0,13, 0, 0, 0,17;
   11, 0, 0, 0, 0, 0,17, 0,19;
   ...
Example: for n=11, row {11,0,0,0,0,0,17,0,19}, when stripped of its zeros and subtracted from 2n=22, gives the partitions {{11,11},{17,5},{19,3}}.
		

Crossrefs

Cf. A085090 (main diagonal), A061397 (column k=0 prepended with (0,2)), A145091 (column k=1 prepended with (0,2,3,0)), A354805.

Programs

  • Mathematica
    nmin = 3; nmax = 16;
    T[n_ /; n >= nmin, k_ /; k >= 0] := If[PrimeQ[n-k] && PrimeQ[n+k], n+k, 0];
    Table[T[n, k], {n, nmin, nmax}, {k, 0, n - nmin}] // Flatten
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