Named after Johann Faulhaber, the rows of Faulhaber's triangle are the coefficients of polynomials that represent sums of integer powers, which are extracted from Faulhaber's formula:








∑

k
=
1


n



k

p


=


1

p
+
1




∑

j
=
0


p





(



p
+
1

j


)




B

j



n

p
+
1
−
j




{\displaystyle \sum _{k=1}^{n}k^{p}={1 \over p+1}\sum _{j=0}^{p}{p+1 \choose j}B_{j}n^{p+1-j}}




where 




B

n




{\displaystyle B_{n}}

 is the nth-Bernoulli number.



The first 5 rows of Faulhaber's triangle, are:

    1
  1/2  1/2
  1/6  1/2  1/3
    0  1/4  1/2  1/4
-1/30    0  1/3  1/2  1/5



Using the third row of the triangle, we have:






∑

k
=
1


n



k

2


=


1
6


n
+


1
2



n

2


+


1
3



n

3




{\displaystyle \sum _{k=1}^{n}k^{2}={1 \over 6}n+{1 \over 2}n^{2}+{1 \over 3}n^{3}}





 Task
 show the first 10 rows of Faulhaber's triangle.
 using the 18th row of Faulhaber's triangle, compute the sum: 




∑

k
=
1


1000



k

17




{\displaystyle \sum _{k=1}^{1000}k^{17}}

 (extra credit).
 See also

 Bernoulli numbers
 Evaluate binomial coefficients
 Faulhaber's formula (Wikipedia)
 Faulhaber's triangle (PDF)


use 5.010;
use List::Util qw(sum);
use Math::BigRat try => 'GMP';
use ntheory qw(binomial bernfrac);
 
sub faulhaber_triangle {
    my ($p) = @_;
    map {
        Math::BigRat->new(bernfrac($_))
          * binomial($p, $_)
          / $p
    } reverse(0 .. $p-1);
}
 
# First 10 rows of Faulhaber's triangle
foreach my $p (1 .. 10) {
    say map { sprintf("%6s", $_) } faulhaber_triangle($p);
}
 
# Extra credit
my $p = 17;
my $n = Math::BigInt->new(1000);
my @r = faulhaber_triangle($p+1);
say "\n", sum(map { $r[$_] * $n**($_ + 1) } 0 .. $#r);