A375534 a(n) = denominator of Sum_{i=1..n} 1/A038603(i).

1, 2, 6, 30, 210, 4830, 140070, 5182590, 222851370, 10474014390, 555122762670, 32752242997530, 2194400280834510, 160191220500919230, 12655106419572619170, 1050373832824527391110, 93483271121382937808790, 9067877298774144967452630, 2022136637626634327741936490

Offset

0,2

Comments

See A375533 (the numerators) for further information.

Links

Alois P. Heinz, Table of n, a(n) for n = 0..313

N. J. A. Sloane, A Nasty Surprise in a Sequence and Other OEIS Stories, Experimental Mathematics Seminar, Rutgers University, Oct 10 2024, Youtube video; Slides [Mentions this sequence]

Example

The first few sums are 0/1, 1/2, 5/6, 31/30, 247/210, 5891/4830, 175669/140070, 6639823/5182590,  ...

Mathematica

a[n_]:=Denominator[Sum[ 1/Part[ResourceFunction["OEISSequence"]["A038603"], i], {i, n}]]; Array[a, 18] (* Stefano Spezia, Sep 06 2024 *)

Crossrefs

Cf. A002110, A038603, A375533, A375805.

Sequence in context: A093449 A083002 A192929 * A077176 A101178 A294925

Adjacent sequences: A375531 A375532 A375533 * A375535 A375536 A375537

Keyword

nonn,frac

Author

N. J. A. Sloane, Sep 06 2024

Extensions

a(0)=1 prepended by Alois P. Heinz, Oct 21 2024

Status

approved