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A329890 a(1) = 1; for n > 1, a(n) = sigma((2^n)-1) - sigma((2^(n-1))-1), where sigma is A000203, the sum of divisors. 4
1, 3, 4, 16, 8, 72, 24, 304, 160, 944, 624, 6576, -544, 14336, 16384, 72544, 19616, 342528, 50688, 1475584, 466176, 3443712, 2657376, 29486880, -3340288, 54808448, 65971360, 306781024, 77647680, 1475408064, 132153344, 5157119680, 3054411072, 12548176896, 13343981568, 130039259136, -28235160128, 228451400256, 269821673472 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..39.

Index entries for sequences related to sigma(n)

FORMULA

a(1) = 1; and for n > 1, a(n) = A075708(n) - A075708(n-1).

PROG

(PARI) A329890(n) = if(1==n, 1, sigma((2^n)-1)-sigma((2^(n-1))-1));

CROSSREFS

From second term onwards, the first differences of A075708.

Cf. A000203, A329637, A329891, A329892.

Sequence in context: A041325 A042541 A325212 * A330299 A047164 A304988

Adjacent sequences:  A329887 A329888 A329889 * A329891 A329892 A329893

KEYWORD

sign

AUTHOR

Antti Karttunen, Dec 08 2019

STATUS

approved

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Last modified April 9 07:30 EDT 2020. Contains 333344 sequences. (Running on oeis4.)