Search: id:A152916
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%I A152916
%S A152916 1,4,10,35,286,969,4495,12341,35990,62196,176851,209934,437989,562475,
%T A152916 971970,1179616,1293699,1975354,2303960,3280455,3737581,5061836,7023974,
%U A152916 12347930,13436856,16435111,23706021,30865405,35999900,39338069
%N A152916 Tetrahedral numbers composed of two primes and one nonprime.
%F A152916 a(n)=A000292(A124588(n-1)), n>1. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), 
               Aug 14 2009]
%e A152916 If n=1(nonprime), n+1=2(prime) and n+2=3(prime), then 1*2*3/6=1=a(1). 
               If n+1=2(prime), n+2=3(prime) and n+3=4(nonprime), then 2*3*4/6=4=a(2). 
               If n+2=3(prime), n+3=4(nonprime) and n+4=5(prime), then 3*4*5/6=10=a(3). 
               If n+4=5(prime), n+5=6(nonprime) and n+6=7(prime), then 5*6*7/6=35=a(4). 
               If n+10=11(prime), n+11=12(nonprime) and n+12=13(prime), then 11*12*13/
               6=286=a(5), etc.
%p A152916 A000292 := proc(n) n*(n+1)*(n+2)/6; end: for n from 1 to 800 do ps := 
               0 ; if isprime(n) then ps := ps+1 ; fi; if isprime(n+1) then ps := 
               ps+1 ; fi; if isprime(n+2) then ps := ps+1 ; fi; if ps = 2 then printf("%d,
               ", A000292(n)) ; fi; od: [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), 
               Aug 14 2009]
%Y A152916 Cf. A000040, A000392, A141468, A152622.
%Y A152916 Sequence in context: A059710 A149177 A149178 this_sequence A108596 A088013 
               A149179
%Y A152916 Adjacent sequences: A152913 A152914 A152915 this_sequence A152917 A152918 
               A152919
%K A152916 nonn
%O A152916 1,2
%A A152916 Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Dec 15 2008

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