A062775 again
Gottfried Helms
helms at uni-kassel.de
Mon Dec 22 07:08:40 CET 2003
T. D. Noe schrieb:
> Because this sequence is multiplicative, we need only give the formula for
> powers of primes. I have computed the sequence for all prime powers <
> 2500, and found the following formulas empirically:
>
> There are 4 cases: for even and odd primes, and for even and odd powers.
>
> For p=2,
> power 2k-1: 2^(3k-1) (2^k - 1)
> power 2k: 2^(3k) (2^(k+1) - 1)
>
> For odd primes p,
> power 2k-1: p^(3k-2) (p^k + p^(k-1) - 1)
> power 2k: p^(3k-1) (p^(k+1) + p^k - 1)
>
> Regards,
>
> Tony
>
>
Hmmm. I think, there is a serious flaw in the formula.
Think of exponent j=3, prime p=7
Then we have
k=2 , j=2k-1 thus formula 3:
> power 2k-1: p^(3k-2) (p^k + p^(k-1) - 1)
7^(3k-2) (7^k + 7^(k-1) -1)
7^4 * ( 7^2 + 7 - 1)
7^4 * 55
The number, that I computed empirically is 55 - just the rightmost
parentheses alone. So may be a typo is in the first part?
For p=11 I got empirically a_3(11) = 121 , but this formula
gives
A_(11) = 11^4 * (121 + 11 -1 ) = 11^4 * 131
where even the right factor 131 is different to my result of counting
and could not be corrected by any correction of the p^(3k-2)-term.
Gottfried Helms
my empirical results for A_3(i) i=1 to 64
i A_3(i)
-----------------
1 1
2 4
3 9
4 20
5 25
6 36
7 55
8 112
9 189
10 100
11 121
12 180
13 109
14 220
15 225
16 448
17 289
18 756
19 487
20 500
21 495
22 484
23 529
24 1008
25 725
26 436
27 2187
28 1100
29 841
30 900
31 1081
32 2048
33 1089
34 1156
35 1375
36 3780
37 973
38 1948
39 981
40 2800
41 1681
42 1980
43 1513
44 2420
45 4725
46 2116
47 2209
48 4032
49 2989
50 2900
51 2601
52 2180
53 2809
54 8748
55 3025
56 6160
57 4383
58 3364
59 3481
60 4500
61 3781
62 4324
63 10395
64 10240
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