A140388 Composites of the form (3*x*y-y-6)/(3*x+1), where x=composite and y=prime.

1, 49, 55, 85, 145, 175, 187, 235, 247, 259, 265, 289, 343, 355, 385, 415, 427, 445, 475, 505, 517, 553, 559, 565, 583, 589, 595, 655, 679, 697, 715, 793, 805, 835, 925, 943, 949, 979, 1015, 1027, 1045, 1057, 1099, 1105, 1147, 1159, 1183, 1219, 1225, 1255

Offset

1,2

Comments

x=c(i)=i-th composite and y=p(j)=j-th prime.

Links

Table of n, a(n) for n=1..50.

Example

If x=1 and y=5, then (3*1*5-5-6)/(3*1+1)=4/4=1=a(1).
If x=9 and y=53, then (3*9*53-53-6)/(3*9+1)=1372/28=49=a(2).
If x=10 and y=59, then (3*10*59-59-6)/(3*10+1)=1705/31=55=a(3).
If x=15 and y=89, then (3*15*89-89-6)/(3*15+1)=3910/46=85=a(4).
If x=25 and y=149, then (3*25*149-149-6)/(3*25+1)=11020/76=145=a(5).
If x=30 and y=179, then (3*30*179-179-6)/(3*30+1)=15925/91=175=a(6),
etc.

Crossrefs

Cf. A002808, A000040.

Sequence in context: A043300 A304008 A305358 * A044863 A162527 A028915

Adjacent sequences: A140385 A140386 A140387 * A140389 A140390 A140391

Keyword

nonn

Author

Juri-Stepan Gerasimov, Aug 28 2008

Status

approved