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A176496 Sum_{k=1..n} 2^nonprime(k). 0
2, 18, 82, 338, 850, 1874, 5970, 22354, 55122, 120658, 382802, 1431378, 3528530, 7722834, 24500050, 58054482, 125163346, 259381074, 527816530, 1601558354 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..20.

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.

PROG

(PARI) a(n) = s = 0; k = 1; while(n, if(!isprime(k), s += 2^k; n--); k++); return(s)

CROSSREFS

Cf. A076793, A018252

Sequence in context: A056664 A213830 A064057 * A091940 A068605 A070171

Adjacent sequences:  A176493 A176494 A176495 * A176497 A176498 A176499

KEYWORD

easy,nonn

AUTHOR

David Lazar (lazar6(AT)illinois.edu), Apr 19 2010

STATUS

approved

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Last modified May 30 00:42 EDT 2017. Contains 287304 sequences.