A179012 Primes that are the sum of three consecutive composite odd numbers.
61, 73, 107, 163, 197, 233, 263, 271, 331, 397, 409, 419, 467, 523, 571, 599, 677, 691, 757, 827, 839, 883, 929, 997, 1039, 1051, 1063, 1097, 1123, 1153, 1163, 1171, 1187, 1223, 1231, 1291, 1301, 1367, 1433, 1493, 1523, 1531, 1571, 1619, 1627, 1637, 1667, 1693, 1783
Offset: 1
Keywords
Examples
15+21+25=61, 21+25+27=73, 33+35+39=107.
Links
- Harvey P. Dale, Table of n, a(n) for n = 1..1000
Programs
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Mathematica
lst={};Do[If[!PrimeQ[n],s=n;k=1,Continue[]];If[!PrimeQ[n+2],s+=n+2;k=2;q=2,If[!PrimeQ[n+4],s+=n+4;k=2;q=4,If[!PrimeQ[n+6],s+=n+6;k=2;q=6]]];If[!PrimeQ[n+q+2],s+=n+q+2;k=3;q+=2,If[!PrimeQ[n+q+4],s+=n+q+4;k=3;q+=4,If[!PrimeQ[n+q+6],s+=n+q+6;k=3;q+=6]]];If[PrimeQ[s],AppendTo[lst,s]],{n,9,6!,2}];lst nn=1001;With[{compodd=Complement[Range[9,nn,2],Prime[Range[ PrimePi[ nn]]]]}, Select[ Total/@ Partition[compodd,3,1],PrimeQ]] (* Harvey P. Dale, Dec 09 2012 *)