login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A069324
Primes in A068949.
4
13, 19, 31, 43, 61, 67, 73, 79, 97, 103, 109, 127, 139, 157, 163, 181, 193, 199, 211
OFFSET
1,1
COMMENTS
Differs from A040047 at the 13th term. - Kevin Buzzard (k.buzzard(AT)imperial.ac.uk), Jun 20 2008
EXAMPLE
a(4)=43 since the fourth prime in A068949 is 43.
PROG
(PARI)
disum(n)= { local(resul) ; resul=0 ; while(n>0, resul += n%10 ; n = (n-n%10)/10 ; ) ; return(resul) ; }
A069324(maxs)= { local(ssqu, su) ; su=1 ; for(s=1, maxs, ssqu=s^2 ; if (disum(ssqu) > su, su=disum(ssqu) ; if( isprime(su), print1(su, ", ") ; ) ; ) ; ) ; }
A069324(200000000) ; \\ R. J. Mathar, May 19 2006
CROSSREFS
KEYWORD
more,nonn,base
AUTHOR
Francois Jooste (phukraut(AT)hotmail.com), Mar 15 2002
EXTENSIONS
a(12) from R. J. Mathar, May 19 2006
a(13)-a(14) from Kevin Buzzard (k.buzzard(AT)imperial.ac.uk), Jun 20 2008
a(15)-a(19) from Giovanni Resta, Jun 27 2018
STATUS
approved