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A117527 Cumulative sums of int(prime*e) which are primes. +0
2
5, 13, 109, 641, 757, 4007, 5387, 7901, 9349, 11467, 23297, 33503, 42193, 57139, 76343, 100213, 209597, 252583, 261631, 373621, 424231, 432287, 503593, 507961, 618593, 699427, 791489, 825389, 895243, 943837, 1212917, 1455901, 1573577 (list; graph; listen)
OFFSET

1,1

COMMENT

Sometimes prime integer sums occur with consecutive primes, as 1601*e and 1607*e.

FORMULA

Beginning with the first prime, multiply by e, take integer, repeat, adding integer sums until a cumulative prime sum occurs. On the first prime, 2, the integer product is 5, prime. Continue to next integer product, add, until the next prime sum, 13.

EXAMPLE

The 4th cumulative sum of integer products is 641, prime.

PROGRAM

UBASIC 10 Ct=1 20 B=nxtprm(B) 22 E=#e 30 C=int(B*E) 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. A117528 A117503.

Sequence in context: A117340 A117437 A106046 this_sequence A004063 A005764 A099974

Adjacent sequences: A117524 A117525 A117526 this_sequence A117528 A117529 A117530

KEYWORD

easy,nonn

AUTHOR

Enoch Haga (Enokh(AT)comcast.net), Mar 25 2006

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Last modified November 18 20:14 EST 2008. Contains 147244 sequences.


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