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A174342 Denominator of ( A164555(n)/A027642(n) +  1/(n+1) ). 3
1, 1, 2, 4, 6, 6, 6, 8, 90, 10, 6, 12, 210, 14, 30, 16, 30, 18, 42, 20, 770, 22, 6, 24, 13650, 26, 54, 28, 30, 30, 462, 32, 5610, 34, 210, 36, 51870, 38, 26, 40, 330, 42, 42, 44, 2070, 46, 6, 48, 324870, 50, 1122, 52, 30, 54, 43890, 56, 5510, 58, 6, 60, 930930 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

The sequence A174341(n)/a(n) = 2, 1, 1/2, 1/4, 1/6, 1/6, 1/6, ... becomes 2, -1, 1/2, -1/4, 1/6,.. under inverse binomial transform: an autosequence, where each second term flips the sign.

LINKS

Table of n, a(n) for n=0..60.

OEIS Wiki, Autosequence

PROG

(PARI)

B(n)=if(n!=1, bernfrac(n), -bernfrac(n));

a(n)=denominator(B(n) + 1/(n + 1));

for(n=0, 60, print1(a(n), ", ")) \\ Indranil Ghosh, Jun 19 2017

(Python)

from sympy import bernoulli, Rational

def B(n):

    return bernoulli(n) if n != 1 else -bernoulli(n)

def a(n):

    return (B(n) + Rational(1, n + 1)).as_numer_denom()[1]

[a(n) for n in range(61)] # Indranil Ghosh, Jun 19 2017

CROSSREFS

Cf. A174341 (numerators).

Sequence in context: A209863 A207540 A050825 * A111150 A166983 A078611

Adjacent sequences:  A174339 A174340 A174341 * A174343 A174344 A174345

KEYWORD

nonn,frac

AUTHOR

Paul Curtz, Mar 16 2010

STATUS

approved

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Last modified September 23 20:42 EDT 2021. Contains 347617 sequences. (Running on oeis4.)