A117527 Cumulative sums of int(prime*e) which are primes.

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

Offset

1,1

Comments

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

Links

Table of n, a(n) for n=1..33.

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.

Prog

(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: A179089 A106046 A180362 * A228280 A155175 A376992

Adjacent sequences: A117524 A117525 A117526 * A117528 A117529 A117530

Keyword

easy,nonn

Author

Enoch Haga, Mar 25 2006

Status

approved