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!)
A304410 Numbers k such that k = Product (p_j^e_j) = Product (p_j*(e_j + 1)). 1
1, 8, 9, 72, 13440, 21120, 24960, 29568, 32640, 34944, 36480, 44160, 45696, 49280, 51072, 54912, 55680, 58240, 59520, 61824, 71040, 71808, 76160, 77952, 78720, 80256, 82560, 83328, 84864, 85120, 90240, 91520, 94848, 97152, 99456, 101760, 103040, 110208, 113280, 114816, 115584, 117120, 119680 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Numbers k such that A000005(k)*A007947(k) = k.

Fixed points of A304409.

All terms are refactorable numbers (A033950).

LINKS

Table of n, a(n) for n=1..43.

Index entries for sequences computed from indices in prime factorization

Index entries for sequences computed from exponents in factorization of n

EXAMPLE

13440 is a term because 13440 = 2^7*3*5*7 = 2*(7 + 1) * 3*(1 + 1) * 5*(1 + 1) * 7*(1 + 1).

MATHEMATICA

a[n_] := Times @@ (#[[1]] (#[[2]] + 1) & /@ FactorInteger[n]); a[1] = 1; Select[Range[120000], a[#] == # &]

CROSSREFS

Cf. A000005, A000026, A007947, A008478, A033950, A036762, A048768, A078779, A190473, A304409.

Sequence in context: A041140 A195940 A195991 * A248290 A256341 A116249

Adjacent sequences:  A304407 A304408 A304409 * A304411 A304412 A304413

KEYWORD

nonn

AUTHOR

Ilya Gutkovskiy, May 12 2018

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 28 21:04 EDT 2022. Contains 354907 sequences. (Running on oeis4.)