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A098206 A first order iteration: n-th term is obtained from (n-1)-th by adding n-th prime and then multiplying by the n-th prime; initial value is 1. 2
1, 12, 85, 644, 7205, 93834, 1595467, 30314234, 697227911, 20219610260, 626807919021, 23191893005146, 950867613212667, 40887307368146530, 1921703446302889119, 101850282654053126116, 6009166676589134444325 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..17.

FORMULA

a(n) = (a(n-1)+prime(n))*prime(n), a(1)=1.

a(n) = product(j=2..n, prime(j)) + sum(k=2..n, prime(k)*product(j=k..n, prime(j))). - Robert Israel, Feb 12 2015

EXAMPLE

n=4: a(4)=(a(3)+7)*7=(85+7)*7=644.

MAPLE

a:= n -> mul(ithprime(j), j=2..n) + add(ithprime(k)*mul(ithprime(j), j=k..n), k=2..n):

seq(a(n), n=1..30); # Robert Israel, Feb 12 2015

MATHEMATICA

f[x_]:=(f[x-1]+Prime[x])*Prime[x]; f[1]=0; Table[f[w], {w, 1, 25}]

CROSSREFS

Cf. A070826, A019461.

Sequence in context: A095267 A118017 A225785 * A104911 A283119 A091119

Adjacent sequences:  A098203 A098204 A098205 * A098207 A098208 A098209

KEYWORD

nonn

AUTHOR

Labos Elemer, Oct 19 2004

STATUS

approved

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Last modified March 30 10:31 EDT 2020. Contains 333125 sequences. (Running on oeis4.)