what is the formula for the sequence: 1, 4, 8, 13, 19, 26?

2 ⤊

2007-03-03 13:06:53 · 5 answers · asked by blubbablub 1 in Science & Mathematics ➔ Mathematics

s(1) = 1
s(n) = s(n-1) + 2 + n

this is a recursive definition of the sequence

2007-03-03 13:19:11 · answer #1 · answered by lucasgw8 2 · 0⤊ 0⤋

The general formula should be,
a(n) = (n/2)(n+3) - 1

2007-03-03 21:19:31 · answer #2 · answered by sahsjing 7 · 0⤊ 0⤋

The formula as a recurrence is:

a[1] = 1
a[n + 1] = a[n] + (n + 2)

2007-03-03 21:13:21 · answer #3 · answered by Puggy 7 · 1⤊ 0⤋

1+3=4
4+4=8
8+5=13
13+6=19
19+7=26
26+8=34
Formula? beats me

2007-03-03 21:18:36 · answer #4 · answered by mike h 4 · 1⤊ 0⤋

explcitly the nth term is 1/2*(n^2 +3n-2)

2007-03-03 21:19:04 · answer #5 · answered by pseudospin 2 · 0⤊ 0⤋