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A117504 Prime at which the cumulative sum in A117503 is prime. 3
37, 137, 151, 173, 409, 467, 503, 677, 937, 1091, 1153, 1229, 1303, 1409, 1453, 1471, 1531, 2137, 2221, 2251, 2393, 2503, 2593, 2633, 2671, 2797, 2837, 3001, 3023, 3089, 3163 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..31.

FORMULA

Multiply consecutive primes by Pi, truncate to integer, sum until a prime sum is reached.

EXAMPLE

In a(1)=37, the cumulative sum of primes 1-12 in A117503 has risen to 613, a prime -- 37 being the 12th prime to be multiplied by Pi, with integer of result added to previous results.

MAPLE

Digits := 30 ; A117504 := proc(nmax) local a, pisum, p ; a := [] ; pisum := 0 ; p :=1 ; while nops(a) <=nmax do while true do pisum := pisum+floor(Pi*ithprime(p)) ; p := p+1 ; if isprime(pisum) then a := [op(a), ithprime(p-1)] ; break ; fi ; od : od : RETURN(a) ; end: a := A117504(30) ; # R. J. Mathar

PROG

UBASIC 10 Ct=1 20 B=nxtprm(B) 30 C=int(pi(B)) 40 D=D+C 41 print Ct, B, C, D 50 if D=prmdiv(D) then print D:stop 55 Ct=Ct+1 60 goto 20

CROSSREFS

Cf. A117503.

Sequence in context: A250899 A139734 A142388 * A055783 A044369 A044750

Adjacent sequences:  A117501 A117502 A117503 * A117505 A117506 A117507

KEYWORD

easy,nonn

AUTHOR

Enoch Haga, Mar 25 2006

EXTENSIONS

Corrected by R. J. Mathar, Oct 26 2006

STATUS

approved

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Last modified April 18 22:08 EDT 2019. Contains 322237 sequences. (Running on oeis4.)