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A050940 Numbers that are not the sum (of a nonempty sequence) of consecutive primes. 4
0, 1, 4, 6, 9, 14, 16, 20, 21, 22, 25, 27, 32, 33, 34, 35, 38, 40, 44, 45, 46, 50, 51, 54, 55, 57, 62, 63, 64, 65, 66, 69, 70, 74, 76, 80, 81, 82, 85, 86, 87, 91, 92, 93, 94, 96, 99, 104, 105, 106, 108, 110, 111, 114, 115, 116, 117, 118, 122, 123, 125 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Where is there a proof that this sequence is infinite? - Carlos Rivera, Apr 17 2002

Moser shows that the average order of A054845 is log(2), and hence this sequence is infinite with lower density at least 1 - log 2 = 0.306.... - Charles R Greathouse IV, Mar 21 2011

LINKS

Franklin T. Adams-Watters, Table of n, a(n) for n = 1..10001

Leo Moser, Notes on number theory. III. On the sum of consecutive primes, Canad. Math. Bull. 6 (1963), pp. 159-161.

EXAMPLE

The number 14 cannot be expressed as a sum of any consecutive subset of the following primes: {2, 3, 5, 7, 11, 13}.

PROG

(BASIC) 10 N=1 20 N=N+1: if N=prmdiv(N) then goto 20 30 P=1 40 P=nxtprm(P):S=P:Q=P: if S>N\2 then print N; :goto 20 50 Q=nxtprm(Q):S=S+Q 60 if S=N then goto 20 70 if S>N then goto 40 80 goto 50

(PARI) is(n)=if(isprime(n), return(0)); my(v, m=1, t); while(1, v=vector(m++); v[m\2]=precprime(n\m); for(i=m\2+1, m, v[i]=nextprime(v[i-1]+1)); forstep(i=m\2-1, 1, -1, v[i]=precprime(v[i+1]-1)); if(v[1]==0, return(1)); t=vecsum(v); if (t==n, return(0)); if(t>n, while(t>n, t-=v[m]; v=concat(precprime(v[1]-1), v[1..m-1]); t+=v[1]), while(t<n, t-=v[1]; v=concat(v[2..m], nextprime(v[m]+1)); t+=v[m])); if(v[1]==0, return(1)); if(t==n, return(0))) \\ Charles R Greathouse IV, May 05 2016

CROSSREFS

Complement of A034707.

Sequence in context: A108634 A135355 A245383 * A190434 A310671 A310672

Adjacent sequences:  A050937 A050938 A050939 * A050941 A050942 A050943

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Jan 02 2000

STATUS

approved

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Last modified October 27 15:27 EDT 2020. Contains 338035 sequences. (Running on oeis4.)