A134733 Concatenation of next n imperfect numbers.

1, 23, 457, 891011, 1213141516, 171819202122, 23242526272930, 3132333435363738, 394041424344454647, 48495051525354555657, 5859606162636465666768, 697071727374757677787980

Offset: 1

Author

Omar E. Pol, Nov 12 2007

Keywords

• base
• easy
• nonn

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..200

Crossrefs

Cf. A053067, A132943, A133013. Imperfect numbers: A132999.

Programs

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 *)