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 A060290 Primes which are sums of Twin Harshad numbers (includes overlaps). 1
 3, 5, 7, 11, 13, 17, 19, 41, 223, 401, 419, 449, 881, 1021, 1259, 1289, 1471, 1601, 1607, 1871, 1999, 2029, 2281, 2549, 2609, 2833, 3041, 3359, 3457, 4001, 4049, 4481, 4801, 4931, 5641, 6329, 7499, 7561, 8081, 8849, 8929, 9613, 9619, 10111, 10321 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 LINKS FORMULA {n in A000040:  (n-1)/2 in A005349 and (n+1)/2 in A005439}. - R. J. Mathar, Dec 20 2013 EXAMPLE a(5)=17, a prime because the first Harshad number is 8 and the second is 9 and 8+9=17. In this sequence overlapping Harshad's are permitted: 1+2=3 and 2+3=5. MAPLE isA005349 := proc(n)     if n mod digsum(n) = 0 then         true;     else         false;     end if; end proc: isA060290 := proc(n)     local h1 ;     if isprime(n) then         h1 := (n-1)/2 ;         if isA005349(h1) and isA005349(h1+1) then             true;         else             false;         end if;     else         false;     end if; end proc: for n from 3 to 20000 do     if isA060290(n) then         printf("%d, ", n) ;     end if; end do: # R. J. Mathar, Dec 20 2013 PROG (UBASIC) 20 A=0; 30 inc A; 40 if Ct=2 then Z=(A-1)+(A-2): if Z=prmdiv(Z) then print A-2; "+"; A-1; "="; Z; "/"; :inc Pt; 50 if Ct=2 then Ct=1:A=A-2; 60 X=1; 70 B=str(A); 80 L=len(B); 90 inc X; 100 S=mid(B, X, 1); 110 V=val(S):W=W+V; 120 if XDt+1 then Ct=0:Dt=0; 150 Dt=Ct:W=0; 160 if A<=10 then 30; 170 print Pt; CROSSREFS A060288, A060289, A005349, A060159. Sequence in context: A264030 A070739 A061244 * A096880 A069458 A062280 Adjacent sequences:  A060287 A060288 A060289 * A060291 A060292 A060293 KEYWORD easy,nonn,base AUTHOR Enoch Haga, Mar 24 2001 STATUS approved

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Last modified July 21 06:55 EDT 2019. Contains 325192 sequences. (Running on oeis4.)