A338482 Least number of centered triangular numbers that sum to n.
1, 2, 3, 1, 2, 3, 4, 2, 3, 1, 2, 3, 4, 2, 3, 4, 5, 3, 1, 2, 3, 4, 2, 3, 4, 5, 3, 4, 2, 3, 1, 2, 3, 4, 2, 3, 4, 2, 3, 4, 2, 3, 4, 5, 3, 1, 2, 3, 4, 2, 3, 4, 5, 3, 4, 2, 3, 4, 5, 3, 4, 2, 3, 1, 2, 3, 4, 2, 3, 4, 5, 3, 4, 2, 3, 4, 2, 3, 4, 5, 3, 4, 2, 3, 1, 2, 3, 4, 2, 3, 4, 2, 3, 4, 2, 3, 4, 5, 3, 4, 5
Offset: 1
Keywords
Links
- Robert Israel, Table of n, a(n) for n = 1..10000
- Eric Weisstein's World of Mathematics, Centered Triangular Number
- Index entries for sequences related to centered polygonal numbers
Programs
-
Maple
f:= proc(n) option remember; local r,i; r:= sqrt(24*n-15)/6+1/2; if r::integer then return 1 fi; 1+min(seq(procname(n-(3*i*(i-1)/2+1)),i=1..floor(r))) end proc: map(f, [$1..200]); # Robert Israel, Nov 13 2020 -
Mathematica
f[n_] := f[n] = Module[{r}, r = Sqrt[24n-15]/6+1/2; If[IntegerQ[r], Return[1]]; 1+Min[Table[f[n-(3i*(i-1)/2+1)], {i, 1, Floor[r]}]]]; Map[f, Range[200]] (* Jean-François Alcover, Sep 16 2022, after Robert Israel *)
Comments