The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
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!)
A351775 Value of all prime numbers p after applying the rule: sigma_n( sigma_n-1( ... sigma_3( sigma_2( sigma_1( sigma_0(p) )))...)) (from sigma_0 up to sigma_n), where sigma_k(m) is the sum of the k-th powers of the divisors of m and p is prime (the choice of the prime p is arbitrary). 0
2, 3, 10, 1134, 1779741927370, 18420061471485119632756156593998809036909505674991629417779936 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,1
COMMENTS
a(6) has 368 digits.
LINKS
FORMULA
a(n) = sigma_n( a(n-1) ) for n >= 1, a(0) = 2.
EXAMPLE
a(0) = sigma_0(2) = 2,
a(1) = sigma_1( sigma_0(2) ) = 3,
a(2) = sigma_2( sigma_1( sigma_0(2) )) = sigma_2(3) = 10,
a(3) = sigma_3( sigma_2( sigma_1( sigma_0(2) ))) = sigma_3(10) = 1134.
...
MATHEMATICA
a[0] = 2; a[n_] := a[n] = DivisorSigma[n, a[n - 1]]; Table[a[n], {n, 0, 6}]
CROSSREFS
Cf. A070239.
Sequence in context: A184163 A218271 A128125 * A070239 A002443 A111788
KEYWORD
nonn
AUTHOR
Wesley Ivan Hurt, Feb 18 2022
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 May 21 11:30 EDT 2024. Contains 372736 sequences. (Running on oeis4.)