A074372 1 + the sum of the distinct primes dividing n.

1, 3, 4, 3, 6, 6, 8, 3, 4, 8, 12, 6, 14, 10, 9, 3, 18, 6, 20, 8, 11, 14, 24, 6, 6, 16, 4, 10, 30, 11, 32, 3, 15, 20, 13, 6, 38, 22, 17, 8, 42, 13, 44, 14, 9, 26, 48, 6, 8, 8, 21, 16, 54, 6, 17, 10, 23, 32, 60, 11, 62, 34, 11, 3, 19, 17, 68, 20, 27, 15, 72, 6, 74, 40, 9, 22, 19, 19, 80, 8

Offset

1,2

Comments

Number of maximal subgroups in dihedral group of order 2n. - Eric M. Schmidt, Oct 14 2014

Links

Table of n, a(n) for n=1..80.

Neville Holmes, Integer Sequences

Formula

a(n) = 1 + A008472(n).

Example

2: 3 (1+2); 3: 4 (1+3); 4: 3 (1+2); 5: 6 (1+5); 6: 6 (1+2+3); ...

Maple

with(numtheory): a:=proc(n) local F: F:=convert(factorset(n), list): 1+sum(F[j], j=1..nops(F)) end: seq(a(n), n=1..90); # Emeric Deutsch, Mar 12 2005

Mathematica

Rest[ Range[0, 20] CoefficientList[ Log[E, Series[(1/(1 - x)) Product[ 1/(1 - x^Prime[j]), {j, 200}], {x, 0, 20}]], x]] (* Robert G. Wilson v, Aug 16 2011 *)
Join[{1}, Array[1+Total[FactorInteger[#][[All, 1]]]&, 80, 2]] (* Harvey P. Dale, Sep 18 2022 *)

Crossrefs

Cf. A001414, A008472, A036288.

Sequence in context: A136195 A117892 A286098 * A331372 A049276 A101684

Adjacent sequences: A074369 A074370 A074371 * A074373 A074374 A074375

Keyword

easy,nonn

Author

W. Neville Holmes, Aug 22 2002

Extensions

Corrected and extended by Emeric Deutsch, Mar 12 2005

Status

approved