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A063845 a(n) = sigma(usigma(n)), where usigma(n) is the sum of unitary divisors of n (A034448) and sigma(n) is the sum of the divisors (A000203). 1
1, 4, 7, 6, 12, 28, 15, 13, 18, 39, 28, 42, 24, 60, 60, 18, 39, 72, 42, 72, 63, 91, 60, 91, 42, 96, 56, 90, 72, 195, 63, 48, 124, 120, 124, 93, 60, 168, 120, 120, 96, 252, 84, 168, 168, 195, 124, 126, 93, 168, 195, 144, 120, 224, 195, 195, 186 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
FORMULA
a(n) = A000203(A034448(n)). - Michel Marcus, Dec 02 2015
MATHEMATICA
usigma[n_] := DivisorSum[n, Boole[CoprimeQ[#, n/#]]*#& ]; a[n_] := DivisorSigma[1, usigma[n]]; Array[a, 60] (* Jean-François Alcover, Dec 02 2015 *)
PROG
(PARI) usigma(n) = sumdiv(n, d, if(gcd(d, n/d)==1, d)) { for (n=1, 1000, write("b063845.txt", n, " ", sigma(usigma(n))) ) } \\ Harry J. Smith, Sep 01 2009
CROSSREFS
Sequence in context: A255248 A122460 A256659 * A188730 A019714 A021681
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Oct 30 2001
STATUS
approved

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Last modified June 16 13:54 EDT 2024. Contains 373429 sequences. (Running on oeis4.)