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A134733
Concatenation of next n imperfect numbers.
1
1, 23, 457, 891011, 1213141516, 171819202122, 23242526272930, 3132333435363738, 394041424344454647, 48495051525354555657, 5859606162636465666768, 697071727374757677787980
OFFSET
1,2
LINKS
MATHEMATICA
Module[{nn=120, in, len}, in=Select[Range[nn], DivisorSigma[1, #]!=2#&]; len= Floor[x/.Last[Solve[(x(x+1))/2==Length[in]]]]; FromDigits[Flatten[ IntegerDigits/@ #]]&/@TakeList[in, Range[len]]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Mar 01 2020 *)
CROSSREFS
Cf. A053067, A132943, A133013. Imperfect numbers: A132999.
Sequence in context: A080479 A053067 A036906 * A328348 A095256 A273008
KEYWORD
base,easy,nonn
AUTHOR
Omar E. Pol, Nov 12 2007
STATUS
approved