1,1
Table of n, a(n) for n=1..9.
1 + prime(34) = 140, which is harmonic, so 34 belongs to the sequence.
isHarmonic[n_] := IntegerQ[n*DivisorSigma[0, n] / DivisorSigma[1, n]]; Select[Range[10^5], isHarmonic[Prime[ # ] + 1] &]
Cf. A001599.
Sequence in context: A197220 A042821 A110070 * A003348 A086488 A195021
Adjacent sequences: A074689 A074690 A074691 * A074693 A074694 A074695
easy,nonn
Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Sep 27 2002
approved
