A172522 - OEIS

A172522

Partial sums of A049094.

6, 18, 36, 56, 77, 101, 131, 167, 207, 249, 297, 351, 411, 474, 540, 612, 690, 770, 854, 944, 1040, 1140, 1242, 1347, 1455, 1565, 1679, 1799, 1925, 2057, 2193, 2331, 2471, 2615, 2762, 2912, 3067, 3223, 3383, 3545, 3713, 3887, 4067, 4253, 4442, 4634, 4832

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

The subsequence of primes in this sequence begins: 101, 131, 167, 3067.

LINKS

Table of n, a(n) for n=1..47.

FORMULA

a(n) = SUM[i=1..n] {i such that 2^i - 1 is divisible by a square}.

EXAMPLE

a(20) = 6 + 12 + 18 + 20 + 21 + 24 + 30 + 36 + 40 + 42 + 48 + 54 + 60 + 63 + 66 + 72 + 78 + 80 + 84 + 90.

CROSSREFS