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A061015
Numerator of Sum_{i=1..n} 1/p(i)^2, p(i) = i-th prime.
10
1, 13, 361, 18589, 2293369, 392915461, 114454369129, 41578647715669, 22089188627685001, 18626778064527922741, 17942190650501641587001, 24603083510737933160021269, 41412850736015889039729489289, 76664929233749755566050236079461
OFFSET
1,2
LINKS
Michael S. Branicky, Table of n, a(n) for n = 1..195
FORMULA
a(1) = 1; a(n) = a(n-1)*p(n)^2+(p(1)*...*p(n-1))^2. - Zak Seidov, Sep 28 2002
MAPLE
summ := 0: for n from 1 to 100 do if (isprime(n)) then summ := summ + 1/n^2; printf("%d, ", numer(summ)); #printf("%d, ", denom(summ)); end if; od; evalf(summ);
MATHEMATICA
Numerator[Accumulate[1/Prime[Range[13]]^2]] (* Jayanta Basu, Jul 14 2013 *)
PROG
(Python)
from sympy import prime
from fractions import Fraction
from itertools import accumulate, count, islice
def A061015gen(): yield from map(lambda x: x.numerator, accumulate(Fraction(1, prime(k)**2) for k in count(1)))
print(list(islice(A061015gen(), 20))) # Michael S. Branicky, Jun 26 2022
CROSSREFS
KEYWORD
easy,nonn,frac
AUTHOR
Winston C. Yang (winston(AT)cs.wisc.edu), May 21 2001
EXTENSIONS
a(14) and beyond from Michael S. Branicky, Jun 26 2022
STATUS
approved