This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
a(4) = 4 because 1! + 3! + 5! + 7! = 5167 is prime.
Select[Range@ 1000, Or[# == 1, PrimeQ@ #] &@ Sum[(2 k - 1)!, {k, #}] &] (* Michael De Vlieger, Dec 01 2015 *)
lista(nn) = { print1(1, ", "); s = 0; for(k=1, nn, s += (2*k-1)!; if(ispseudoprime(s), print1(k, ", ")); ); }
Table[Sum[(2*i)!, {i,n}], {n,15}] (* Stefan Steinerberger, Mar 25 2008 *)
Accumulate[(2*Range[20])!] (* Harvey P. Dale, Nov 12 2016 *)
for(n=1,25, print1(sum(k=1,n, (2*k)!), ", ")) \\ G. C. Greubel, Sep 29 2017
from math import factorial def a(n): return sum(factorial(2*k) for k in range(1, n+1)) print([a(n) for n in range(1, 16)]) # Michael S. Branicky, Feb 26 2021
A138525:=n->add((2*k)!, k=0..n): seq(A138525(n), n=0..15); # Wesley Ivan Hurt, Dec 01 2015
Table[Sum[(2i)!, {i, 0, n}], {n, 0, 15}] (* Stefan Steinerberger, Mar 25 2008 *)
a(n) = sum(k=0, n, (2*k)!); \\ Altug Alkan, Dec 01 2015
Comments