A176496 - OEIS

A176496

a(n) = Sum_{k=1..n} 2^nonprime(k).

2, 18, 82, 338, 850, 1874, 5970, 22354, 55122, 120658, 382802, 1431378, 3528530, 7722834, 24500050, 58054482, 125163346, 259381074, 527816530, 1601558354, 5896525650, 14486460242, 31666329426, 66026067794, 134745544530, 409623451474, 959379265362, 2058890893138

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OFFSET

1,1

LINKS

Andrew Howroyd, Table of n, a(n) for n = 1..500

FORMULA

a(1) = 2, a(n) = a(n-1) + 2^A018252(n).

EXAMPLE

a(2) = 2 + 2^A018252(2) = 2 + 2^4 = 18 ; a(3) = 18 + 2^A018252(3) = 18 + 2^6 = 82.

MATHEMATICA

With[{t=Select[Range[50], !PrimeQ[#]&]}, Accumulate[2^t]] (* Harvey P. Dale, Feb 14 2023 *)

PROG