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A046915
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Sum of divisors of 10^n.
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3
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1, 18, 217, 2340, 24211, 246078, 2480437, 24902280, 249511591, 2497558338, 24987792457, 249938963820, 2499694822171, 24998474116998, 249992370597277, 2499961853010960, 24999809265103951, 249999046325618058, 2499995231628286897
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| A072692(n) = A049000(n) + A046915(n).
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LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 0..1000
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FORMULA
| 1/4*(2^(n+1)-1)*(5^(n+1)-1). E.g. a(1)=1/4*(2^2-1)*(5^2-1)=18. - Vladeta Jovovic (vladeta(AT)eunet.rs), Dec 18 2001
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EXAMPLE
| At 10^1 the factors are 1, 2, 5, 10. The sum of these factors is 18: 1 + 2 + 5 + 10.
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PROG
| (MAGMA) [1/4*(2^(n+1)-1)*(5^(n+1)-1): n in [0..20]]; // Vincenzo Librandi, Oct 03 2011
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CROSSREFS
| Cf. A000203 (sigma(n)), A049000, A072692.
Sequence in context: A019757 A021503 A025470 * A041616 A019333 A021454
Adjacent sequences: A046912 A046913 A046914 * A046916 A046917 A046918
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KEYWORD
| easy,nonn
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AUTHOR
| Enoch Haga (Enokh(AT)comcast.net)
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