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

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

Cf. A000040, A014491, A049093, A049096, A049095, A001220.

Sequence in context: A333821 A358843 A328586 * A152539 A069958 A028896

Adjacent sequences: A172519 A172520 A172521 * A172523 A172524 A172525

Keyword

nonn

Author

Jonathan Vos Post, Feb 06 2010

Extensions

More terms from R. J. Mathar, Feb 16 2010

Status

approved