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A133760
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Sum of the number of divisors of the numbers between prime(n) and prime(n+1).
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1
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0, 3, 4, 11, 6, 13, 6, 14, 25, 8, 27, 16, 8, 16, 29, 28, 12, 29, 18, 12, 28, 19, 32, 46, 21, 8, 20, 12, 22, 81, 20, 36, 8, 59, 12, 38, 34, 18, 39, 32, 18, 58, 14, 21, 12, 80, 70, 25, 12, 24, 34, 20, 56, 43, 34, 38, 16, 40, 26, 8, 65, 96, 24, 16, 22, 99, 40, 62, 12, 32, 30, 61, 40, 44
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OFFSET
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1,2
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LINKS
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Table of n, a(n) for n=1..74.
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FORMULA
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a(n) = sum_{ prime(n)<i<prime(n+1)} A000005(i).
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EXAMPLE
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a(1) = 0 because there is no composite number between the primes 2 and 3.
a(4)= 11 = A000005(8)+A000005(9)+A000005(10), indices delimited by prime(4) = 7 and prime(5) = 11.
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MAPLE
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A000005 := proc(n) numtheory[tau](n) ; end: A133760 := proc(n) add( A000005(i), i=ithprime(n)+1..ithprime(n+1)-1) ; end: seq(A133760(n), n=1..80);
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MATHEMATICA
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f[n_] := Plus @@ Flatten@ DivisorSigma[0, { Range[ Prime[n] + 1, Prime[n + 1] - 1]}]; Array[f, 74] (* Robert G. Wilson v *)
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CROSSREFS
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Cf. A000005.
Sequence in context: A218293 A085386 A180696 * A197953 A198299 A175317
Adjacent sequences: A133757 A133758 A133759 * A133761 A133762 A133763
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KEYWORD
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easy,nonn
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AUTHOR
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Giovanni Teofilatto, Jan 05 2008
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EXTENSIONS
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Edited, corrected and extended by Robert G. Wilson v and R. J. Mathar, Jan 06 2008
Name corrected by Jon Perry, Nov 23 2012
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STATUS
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approved
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