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A173470 Semiprimes in A023037. 0
85, 781, 137257, 28531167061 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
The terms a(5) etc. have at least 63 digits (if they exist), so the pattern of terms does not continue as in A001039. [From R. J. Mathar, Feb 27 2010]
LINKS
MATHEMATICA
f1[n_]:=Module[{s=0}, Do[s+=n^a, {a, 0, n-1}]; s]; f2[n_]:=Last/@FactorInteger[n]=={1, 1}||Last/@FactorInteger[n]=={2}; Select[Table[f1[n], {n, 50}], f2[ # ]&]
CROSSREFS
Sequence in context: A339870 A183777 A297599 * A202009 A194533 A069308
KEYWORD
nonn
AUTHOR
STATUS
approved

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Last modified May 22 20:45 EDT 2024. Contains 372758 sequences. (Running on oeis4.)