OFFSET
0,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..1000
Jackson Earles, Aaron Li, Adam Nelson, Marlo Terr, Sarah Arpin, and Ilia Mishev Binomial Transforms of Sequences, CU Boulder Experimental Math Lab, Spring 2019.
FORMULA
a(n) = Sum_{k=0..n} (-1)^k*binomial(n,k)*A003418(k+1).
Formula for values modulo 10: (Proof by considering the formula modulo 10)
a(n) (mod 10) = 1, if n = 0, 3, 4 (mod 5),
a(n) (mod 10) = 9, if n = 1 (mod 5),
a(n) (mod 10) = 3, if n = 2 (mod 5).
EXAMPLE
For n = 3, a(3) = binomial(3,0)*1 - binomial(3,1)*2 + binomial(3,2)*6 - binomial(3,3)*12 = 1.
MAPLE
b:= proc(n) option remember; `if`(n=0, 1, ilcm(n, b(n-1))) end:
a:= n-> add(b(i+1)*binomial(n, i)*(-1)^i, i=0..n):
seq(a(n), n=0..30); # Alois P. Heinz, Apr 29 2019
MATHEMATICA
b[n_] := b[n] = If[n == 0, 1, LCM[n, b[n - 1]]];
a[n_] := Sum[b[i + 1] Binomial[n, i] (-1)^i, {i, 0, n}];
a /@ Range[0, 30] (* Jean-François Alcover, Nov 27 2020, after Alois P. Heinz *)
PROG
(Sage)
def SIbinomial_transform(N, seq):
BT = [seq[0]]
k = 1
while k< N:
next = 0
j = 0
while j <=k:
next = next + (((-1)^j)*(binomial(k, j))*seq[j])
j = j+1
BT.append(next)
k = k+1
return BT
LCMSeq = []
for k in range(1, 26):
LCMSeq.append(lcm(range(1, k+1)))
SIbinomial_transform(25, LCMSeq)
(PARI) a(n) = sum(k=0, n, (-1)^k*binomial(n, k)*lcm(vector(k+1, i, i))); \\ Michel Marcus, Apr 30 2019
CROSSREFS
KEYWORD
sign
AUTHOR
Sarah Arpin, Apr 29 2019
STATUS
approved