Search: id:A140890
Results 1-1 of 1 results found.

%I A140890
%S A140890 10,60,52,68,131,112,128,223,172,97,420,113,127,407,149,308,330,352,181,
%T A140890 780,0,211,679,472,241,508,532,548,564,293,307,941,0,668,696,712,367,
%U A140890 752,772,397,810,419,421,1303,892,457,1391,479,487,990,1012,0,1044,0
%N A140890 Sum of primes in { 10n-9, 10n-7, 10n-3, 10n-1 }.
%F A140890 a(n)= (10n-9) isprime (10n-9) + (10n-7) isprime (10n-7) + (10n-3) isprime 
               (10n-3) + (10n-1) isprime (10n-1), where isprime = A010051.- M. F. 
               Hasier, Jun 15 2008
%e A140890 If n=1, then a(1)=A030430 (-) + A030431 (1) + A030432 (1) + A030433 (-) 
               =0+3+7+0=10
%e A140890 If n=11, then a(11)=A030430 (6) + A030431 (9) + A030432 (7) + A030433 
               (6)=101+103+107+109=420
%e A140890 If n=21, then a(21)=A030430 (-) + A030431 (-) + A030432 (-) + A030433 
               (-) =0+0+0+0=0
%t A140890 f[n_]:=Plus@@Select[10n-{9,7,3,1},PrimeQ]; Table[f[n],{n,60}] (*Chandler*)
%o A140890 (PARI) a(n)=(10*n-9)*isprime(10*n-9) + (10*n-7)*isprime(10*n-7) + (10*n-3)*isprime(10*n-3) 
               + (10*n-1)*isprime(10*n-1) //M. F. Hasier, Jun 15 2008
%Y A140890 Cf. A030430, A030431, A030432, A030433.
%Y A140890 Sequence in context: A061001 A055586 A054489 this_sequence A055714 A046762 
               A066290
%Y A140890 Adjacent sequences: A140887 A140888 A140889 this_sequence A140891 A140892 
               A140893
%K A140890 nonn
%O A140890 1,1
%A A140890 Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Jul 06 2008
%E A140890 Corrected and extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), 
               Feb 20 2009

Search completed in 0.001 seconds