A241525 a(n) is the smallest start of a run of exactly n consecutive primes such that the sum of the digits of each prime is composite.
19, 17, 13, 521, 509, 503, 499, 491, 14153, 25793, 25771, 37663, 37657, 98729, 98717, 98713, 98711, 98689, 98669, 98663, 98641, 98639, 98627, 98621, 98597, 98573, 69794393, 69794383, 268684679, 268684651, 268684627, 329788829, 545497787, 545497769, 545497759, 545497753, 545497747, 545497741, 545497727, 545497723, 545497691, 545497681, 545497679, 545497637, 545497633, 545497609
Offset: 1
Examples
a(3)=13 because the run of the 3 consecutive primes {13, 17, 19} is such that the sum of digits for each prime is {4, 8, 10}.
Crossrefs
Cf. A240598.
Programs
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UBASIC
10 P=1:KM=0:K=0:'puzzle 1290, Meller 20 P=nxtprm(P):if P>2^32-20 then end 30 gosub *SODP:if S<>prmdiv(S) then K=K+1:Q=P:goto 20 40 if K>KM then print K, Q:KM=K 50 K=0:goto 20 200 *SODP:S=0:L=alen(P) 210 for I=1 to L:D=val(mid(str(P), I+1, 1)) 220 S=S+D:next I 230 return
Comments