A366622
Sum of the divisors of 6^n-1.
Original entry on oeis.org
6, 48, 264, 1824, 9672, 67584, 335928, 2367552, 13031040, 94708224, 454285152, 3523559424, 15677418768, 113738502240, 599516366592, 4210539708672, 20465720064000, 154928015278080, 735060126170880, 5906693566844928, 26937015875831424, 188358079273592832
Offset: 1
a(4)=1824 because 6^4-1 has divisors {1, 5, 7, 35, 37, 185, 259, 1295}.
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a:=n->numtheory[sigma](6^n-1):
seq(a(n), n=1..100);
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DivisorSigma[1, 6^Range[30]-1]
A366653
Sum of the divisors of 8^n-1.
Original entry on oeis.org
8, 104, 592, 8736, 38912, 473600, 2466048, 38054016, 155493536, 2015330304, 10359014400, 166290432000, 636328345600, 7645340651520, 42424026529792, 648494317126656, 2599936977797120, 32817383473149440, 164708609085669376, 3010983668199456768
Offset: 1
a(5)=38912 because 8^5-1 has divisors {1, 7, 31, 151, 217, 1057, 4681, 32767}.
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a:=n->numtheory[sigma](8^n-1):
seq(a(n), n=1..100);
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DivisorSigma[1, 8^Range[30]-1]
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[sigma(8**n-1, 1) for n in range(1, 21)] # Stefano Spezia, Aug 02 2025
A366662
Sum of the divisors of 9^n-1.
Original entry on oeis.org
15, 186, 1680, 15876, 123690, 1541568, 8992680, 111757968, 967814400, 9366647892, 62424587520, 852903426816, 4766016364260, 55176998178240, 550081165885440, 4829754617483040, 31725040326819840, 471309320999516160, 2535353780263288800, 33995669076586206864
Offset: 1
a(2)=186 because 9^2-1 has divisors {1, 2, 4, 5, 8, 10, 16, 20, 40, 80}.
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a:=n->numtheory[sigma](9^n-1):
seq(a(n), n=1..30);
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DivisorSigma[1, 9^Range[30]-1]
A366603
Sum of the divisors of 4^n-1.
Original entry on oeis.org
4, 24, 104, 432, 1536, 8736, 22528, 111456, 473600, 1999872, 5909760, 38054016, 89522176, 462274560, 2015330304, 7304603328, 22907191296, 166290432000, 366506672128, 2220409884672, 7645340651520, 29833839544320, 95821839806976, 648494317126656
Offset: 1
a(4)=432 because 4^4-1 has divisors {1, 3, 5, 15, 17, 51, 85, 255}.
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a:=n->numtheory[sigma](4^n-1):
seq(a(n), n=1..100);
-
DivisorSigma[1,4^Range[30]-1] (* Paolo Xausa, Oct 14 2023 *)
A366613
Sum of the divisors of 5^n-1.
Original entry on oeis.org
7, 60, 224, 1736, 6048, 49920, 136724, 1107792, 3718400, 27060480, 85449224, 869499904, 2136230474, 15820920000, 61359427584, 461863805760, 1338408456700, 13177159680000, 33558717136896, 301282248701952, 863701914880000, 6313641012910080, 20863951122979048
Offset: 1
a(3)=224 because 5^3-1 has divisors {1, 2, 4, 31, 62, 124}.
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a:=n->numtheory[sigma](5^n-1):
seq(a(n), n=1..100);
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DivisorSigma[1, 5^Range[30]-1]
A366634
Sum of the divisors of 7^n-1.
Original entry on oeis.org
12, 124, 780, 7812, 33624, 354640, 1704240, 18929096, 97036800, 800520192, 3958188480, 56928231360, 193778020824, 1830926384640, 11181115146240, 115997032277280, 465294239722800, 5175558387507200, 22852200371636160, 287850454432579584, 1318081737957660000
Offset: 1
a(5)=33624 because 7^5-1 has divisors {1, 2, 3, 6, 2801, 5602, 8403, 16806}.
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a:=n->numtheory[sigma](7^n-1):
seq(a(n), n=1..100);
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DivisorSigma[1, 7^Range[30]-1]
A366576
Sum of the divisors of 3^n-1.
Original entry on oeis.org
3, 15, 42, 186, 399, 1680, 3282, 15876, 31836, 123690, 277344, 1541568, 2391486, 8992680, 25483332, 111757968, 193819392, 967814400, 1744488660, 9366647892, 16912999320, 62424587520, 144219337920, 852903426816, 1397135488896, 4766016364260, 12477973754400
Offset: 1
a(4)=186 because 3^4-1 has divisors {1, 2, 4, 5, 8, 10, 16, 20, 40, 80}.
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a:=n->numtheory[sigma](3^n-1):
seq(a(n), n=1..100);
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DivisorSigma[1,3^Range[30]-1] (* Paolo Xausa, Oct 15 2023 *)
A366668
Sum of the divisors of 10^n+1.
Original entry on oeis.org
3, 12, 102, 1344, 10212, 109104, 1010004, 10909104, 105882372, 1413350400, 10102223208, 114737461440, 1021097900424, 10921790676000, 104844305394000, 1355394166984704, 10073631600468000, 110177492439680640, 1010002989998020008, 10909090909090909104
Offset: 0
a(3)=1344 because 10^3+1 has divisors {1, 7, 11, 13, 77, 91, 143, 1001}.
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a:=n->numtheory[sigma](10^n+1):
seq(a(n), n=0..100);
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DivisorSigma[1, 10^Range[0,19] + 1] (* Paul F. Marrero Romero, Nov 12 2023 *)
Showing 1-8 of 8 results.