login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A324294 a(n) = A002487(1+sigma(n)). 10
1, 1, 3, 1, 3, 5, 4, 1, 3, 7, 5, 7, 4, 7, 7, 1, 7, 3, 8, 13, 6, 11, 7, 9, 1, 13, 11, 10, 5, 15, 6, 1, 9, 11, 9, 7, 10, 9, 10, 19, 13, 11, 12, 21, 13, 15, 9, 11, 7, 9, 15, 16, 11, 13, 15, 13, 14, 19, 9, 29, 6, 11, 18, 1, 21, 19, 14, 7, 11, 19, 15, 9, 18, 17, 11, 22, 11, 29, 14, 25, 9, 7, 21, 16, 19, 17, 13, 31, 19, 29, 13, 29, 8, 19, 13, 13, 16 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
LINKS
FORMULA
a(n) = A002487(1+sigma(n)).
a(2^n) = 1 for all n >= 0, but also for some other numbers, e.g., a(25) = 1.
MATHEMATICA
A002487[m_] := Module[{a = 1, b = 0, n = m}, While[n > 0, If[OddQ[n], b = a + b, a = a + b]; n = Floor[n/2]]; b];
a[n_] := A002487[1 + DivisorSigma[1, n]];
Table[a[n], {n, 1, 100}] (* Jean-François Alcover, Mar 11 2023 *)
PROG
(PARI)
A002487(n) = { my(s=sign(n), a=1, b=0); n = abs(n); while(n>0, if(bitand(n, 1), b+=a, a+=b); n>>=1); (s*b); };
A324294(n) = A002487(1+sigma(n));
(Python)
from functools import reduce
from sympy import divisor_sigma
def A324294(n): return reduce(lambda x, y:(x[0], x[0]+x[1]) if int(y) else (x[0]+x[1], x[1]), bin(divisor_sigma(n)+1)[-1:1:-1], (1, 0))[1] # Chai Wah Wu, Jun 19 2022
CROSSREFS
Sequence in context: A122582 A173039 A016471 * A082082 A016646 A345943
KEYWORD
nonn
AUTHOR
Antti Karttunen, Feb 22 2019
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 20 21:09 EDT 2024. Contains 373532 sequences. (Running on oeis4.)