A067110 - OEIS

%I #19 Sep 11 2024 14:49:02

%S 1,4,23,138,8418,574905,40639850,3061183528,235711131719,

%T 18272180753428,1473194573245205,119650320669661386,

%U 9903829063833316444,838829650246380538698,71863149914400283955531,6186643877145221295909277,535707117543711207668507898

%N a(n) = floor(concatenation of first n primes / sum of first n primes).

%H Harry J. Smith, <a href="/A067110/b067110.txt">Table of n, a(n) for n = 1..100</a>

%e a(4) = floor(2357/17) = floor(138.647...) = 138.

%t f[n_] := (a = {}; k = 1; While[ k < n + 1, a = Join[a, IntegerDigits[ Prime[k]]]; k++ ]; FromDigits[a]); Table[ Floor[ f[n]/Sum[ Prime[i], {i, 1, n} ]], {n, 1, 20} ]

%o (PARI) Concat(a, b)= { return(a*10^(1+logint(b,10)) + b) }

%o { my(c=0, s=0); forprime (p=2, prime(20), s+=p; c=Concat(c, p); print1( c\s, ", ") ) } \\ _Harry J. Smith_, May 22 2010

%Y Cf. A007504, A019518.

%K easy,nonn,base

%O 1,2

%A _Amarnath Murthy_, Jan 08 2002

%E More terms from _Robert G. Wilson v_, Jan 08 2002

%E Edited by _Charles R Greathouse IV_, Apr 28 2010