OFFSET
1,2
COMMENTS
Partial sums of sequence starting with a(1) = 1 and for which a(n) is smallest number which avoids any 3-term G.P. (geometric progression). The subsequence of primes in this partial sum begins: 3, 11, 17, 53, 263, 349, 557, 677, 719, 1061, 1229, 1667, 1877, 2179, 3019, 3203. The subsequence of squares begins: 1, 1600. subsequence of powers of 2 begins: 1, 32, 128.
FORMULA
a(n) = Sum_{i=1..n} A000452(i).
EXAMPLE
a(9) = 1 + 2 + 3 + 5 + 6 + 7 + 8 + 10 + 11 = 53 is prime.
CROSSREFS
KEYWORD
nonn
AUTHOR
Jonathan Vos Post, Mar 25 2010
STATUS
approved