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A178155 Partial sums of A003407 (starting at n=1). 0

%I

%S 1,3,7,17,37,85,189,471,967,2033,4493,10621,23461,52841,127745,340473,

%T 708489,1367785,2738841,5675977,12313209,27929825,66361381,162909213,

%U 361319381,780460693,1722272781,3904263759,9528920767,24294326763,66213009251,187941084483,395937137667,756194730883,1395731222259,2540709556499,4903320997075,9814465115099

%N Partial sums of A003407 (starting at n=1).

%C Partial sums of number of permutations with no 3-term arithmetic progression. The subsequence of primes in this partial sum begins with 4 in a row: 3, 7, 17, 37, 967, 4493, 66361381, 780460693, 9814465115099, 1094158908254653, ...

%F a(n) = Sum_{i=1..n} A003407(i).

%e a(11) = 1 + 2 + 4 + 10 + 20 + 48 + 104 + 282 + 496 + 1066 + 2460 = 4493 is prime.

%Y Cf. A003407.

%K nonn

%O 1,2

%A _Jonathan Vos Post_, May 21 2010

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Last modified January 27 05:57 EST 2023. Contains 359837 sequences. (Running on oeis4.)