A258621 Decimal expansion of sum(1/A030450).

2, 2, 5, 6, 9, 4, 7, 4, 5, 8, 5, 2, 6, 5, 9, 7, 9, 5, 5, 4, 6, 2, 7, 3, 6, 7, 2, 4, 4, 4, 2, 3, 4, 2, 2, 1, 0, 5, 5, 9, 2, 3, 6, 5, 0, 8, 8, 9, 3, 6, 9, 5, 9, 5, 3, 3, 4, 6, 0, 0, 4, 9, 6, 0, 9, 2, 6, 7, 5, 4, 9, 2, 8, 1, 7, 5, 2, 2, 0, 0, 6, 7, 7, 6, 1, 4, 8, 9, 6, 2, 1, 3, 3, 1, 7, 7, 7, 7, 7, 7, 2, 8, 5, 6, 4, 6

Offset: 1

Author

Jani Melik, Jun 06 2015

Keywords

• nonn
• cons

Examples

			2.2569474585265979554627367244423422105592365088936959533....
		

Crossrefs

Cf. A030450.

Programs

C

#include 
#include 
#define dBIT   512
#define dLIST  n, t, u
int main (void) {
mpfr_t dLIST;
mpfr_rnd_t trnd;
unsigned int i;
trnd = MPFR_RNDU;
mpfr_inits2 (dBIT, dLIST, (mpfr_ptr) 0);
mpfr_set_d (n, 1.0, trnd);
mpfr_set_d (t, 1.0, trnd);
for (i = 1; i <= 9; i++) {
    mpfr_mul_ui (t, t, i, trnd);
    mpfr_mul (t, t, t, trnd);
    mpfr_set_d (u, 1.0, trnd);
    mpfr_div (u, u, t, trnd);
    mpfr_add (n, n, u, trnd);
}
mpfr_printf ("%.106Rg", n);
mpfr_clears (dLIST, (mpfr_ptr) 0);
return 0;
}

Sage

def A030450(n) :
   return prod((n-i+1)^(2^i) for i in (1..n))
N(sum(1/A030450(n) for n in (0..9)), digits=106)