A387894 a(n) is the permanent of the n X n matrix containing the first n^2 composites in increasing order.

1, 4, 84, 5432, 900792, 290225653, 169314109992, 159469813531214, 230347718608898256, 475890725730586499604, 1373277987153582610447358, 5266535416282904594552044881, 26432142517662167751246728249072, 169994984953941647545902105154652596, 1366482693585758120105860031906154246976

Offset

0,2

Links

Table of n, a(n) for n=0..14.

Example

a(3) = 5432:
  [ 4,  6,  8]
  [ 9, 10, 12]
  [14, 15, 16]

Mathematica

composite[n_] := FixedPoint[n + PrimePi[#] + 1 &, n + PrimePi[n] + 1]; a[n_] := Permanent[ArrayReshape[Array[composite, n^2], {n, n}]]; Join[{1}, Array[a, 14]] (* after A321685 *)

Crossrefs

Cf. A114533, A321685, A387895.

Sequence in context: A012189 A012076 A173211 * A109901 A367522 A015018

Adjacent sequences: A387891 A387892 A387893 * A387895 A387896 A387897

Keyword

nonn

Author

Stefano Spezia, Sep 11 2025

Status

approved