login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A060437 a(n) is the number of different degrees in the sequence of the degrees of the irreducible representations of the symmetric group S_n, i.e., count each degree only once. 5

%I

%S 1,1,2,3,4,5,7,12,15,22,28,38,45,52,81,107,130,179,194,280,348,438,

%T 502,693,848,1037,1274,1594,1847,2473,2851,3652,4271,5137,6140,7995,

%U 9103,11046,12978,16216,18348,23153,26239,31880,37582,45144,51469,63571,71910

%N a(n) is the number of different degrees in the sequence of the degrees of the irreducible representations of the symmetric group S_n, i.e., count each degree only once.

%C The total number of irreducible representations of S_n is the partition function p(n) (sequence A000041) - this is the total number of the degrees counting multiplicities.

%C Also a(n) = number of distinct values of A153452(m) when A056239(m) is equal to n. - _Naohiro Nomoto_, Dec 31 2008

%e a(6) = 5 because the degrees for S_6 are 1,1,5,5,5,5,9,9,10,10,16 and counting each degree only once only 5 numbers remain: 1,5,9,10,16.

%p with(numtheory):

%p g:= proc(n) option remember; `if`(n=1, 1,

%p add(g(n/q*`if`(q=2, 1, prevprime(q))), q=factorset(n)))

%p end:

%p b:= proc(n, i) option remember; `if`(n=0 or i<2, [2^n],

%p [seq(map(p->p*ithprime(i)^j, b(n-i*j, i-1))[], j=0..n/i)])

%p end:

%p a:= n-> nops(map(g, {b(n, n)[]})):

%p seq(a(n), n=1..30); # _Alois P. Heinz_, Aug 09 2012

%t g[n_] := g[n] = If[n == 1, 1, Sum[g[n/q*If[q == 2, 1, NextPrime[q, -1]]], {q, FactorInteger[n][[All, 1]]}]]; b[n_, i_] :=b[n, i] = If[n == 0 || i<2, {2^n}, Flatten @ Table[ Map[Function[{p}, p*Prime[i]^j], b[n-i*j, i-1]], {j, 0, n/i}] ]; a[n_] := Length[Union[g /@ b[n, n]]]; Table[a[n], {n, 1, 30}] (* _Jean-Fran├žois Alcover_, Apr 15 2015, after _Alois P. Heinz_ *)

%Y Cf. A000041, A060240, A215366.

%K nonn

%O 1,3

%A Avi Peretz (njk(AT)netvision.net.il), Apr 07 2001

%E More terms from _Vladeta Jovovic_, May 20 2003

%E a(22)-a(49) from _Alois P. Heinz_, Aug 09 2012

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 21 07:23 EDT 2019. Contains 321367 sequences. (Running on oeis4.)