[go: up one dir, main page]

login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A137790
a(n) = 8^n-7^n-6^n-5^n-4^n-3^n-2^n.
0
3761, 77325, 896849, 8869821, 81550961, 719926125, 6196609169, 52439953821, 438516694961, 3635082523725, 29935019892689, 245264010263421, 2001462391659761, 16280541150478125, 132087583623451409, 1069376609438070621, 8642407976463949361, 69743131733050637325
OFFSET
5,1
COMMENTS
The sequence starts at n=5 as for n<5 the result is negative. - Tanya Khovanova, Jul 05 2021
LINKS
FORMULA
G.f.: x^5*(23345280*x^6 -29177136*x^5 +12543396*x^4 -1855156*x^3 -112345*x^2 +54310*x -3761)/((2*x -1)*(3*x -1)*(4*x -1)*(5*x -1)*(6*x -1)*(7*x -1)*(8*x -1)). - Colin Barker, Nov 05 2012
EXAMPLE
a(5) = 8^5 - 7^5 - 6^5 - 5^5 - 4^5 - 3^5 - 2^5 = 3761. - Tanya Khovanova, Jul 05 2021
MATHEMATICA
Array[8^#-7^#-6^#-5^#-4^#-3^#-2^# &, 10, 0]
LinearRecurrence[{35, -511, 4025, -18424, 48860, -69264, 40320}, {3761, 77325, 896849, 8869821, 81550961, 719926125, 6196609169}, 20] (* Harvey P. Dale, Sep 04 2017 *)
PROG
(Python)
def a(n): return 8**n - 7**n - 6**n - 5**n - 4**n - 3**n - 2**n
print([a(n) for n in range(5, 23)]) # Michael S. Branicky, Jul 05 2021
CROSSREFS
Sequence in context: A133969 A133970 A252564 * A300796 A338545 A284079
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
More terms from Colin Barker, Nov 05 2012
Offset corrected by Tanya Khovanova, Jul 05 2021
STATUS
approved