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A172522 Partial sums of A049094. 0
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

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

Sequence in context: A111147 A333821 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

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Last modified August 11 06:25 EDT 2020. Contains 336422 sequences. (Running on oeis4.)