A141636 Primes of the form c(c(c(i)-3)-3)-3, where A002808(i)=c(i)=i-th composite.

7, 11, 13, 17, 19, 31, 37, 43, 59, 61, 79, 83, 97, 109, 137, 149, 151, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 251, 269, 293, 307, 313, 317, 337, 347, 349, 353, 373, 379, 383, 397, 419, 421, 431, 433, 443, 457, 461, 463, 467, 487, 491, 503, 509, 541, 547, 557, 563, 569, 571, 577, 587, 593

Offset

1,1

Links

Table of n, a(n) for n=1..64.

Example

If i=1, then c(c(c(1)-3)-3)-3=c(c(4-3)-3)-3=c(4-3)-3=4-3=1 (nonprime).
If i=2, then c(c(c(2)-3)-3)-3=c(c(6-3)-3)-3=c(8-3)-3=c(5)-3=10-3=7=a(1).

Maple

A002808 := proc(n) option remember ; if n = 1 then 4; else for a from procname(n-1)+1 do if not isprime(a) then RETURN(a); fi; od: fi; end: rep := 3: for n from 1 to 800 do arep := n ; for i from 1 to rep do arep := A002808(arep)-3 ; od: if isprime(arep) then printf("%d, ", arep) ; fi; od: # R. J. Mathar, Sep 05 2008

Crossrefs

Cf. A002808, A000040.

Sequence in context: A296928 A358743 A243768 * A214786 A176834 A098414

Adjacent sequences: A141633 A141634 A141635 * A141637 A141638 A141639

Keyword

nonn

Author

Juri-Stepan Gerasimov, Sep 03 2008

Extensions

Removed erroneous examples, correctly roughly 10 percent of the values. - R. J. Mathar, Sep 05 2008

Status

approved