A158054 - OEIS

%I #8 Feb 17 2019 20:22:29

%S 2,3,7,23,23,29,67,97,131,47,113,59,173,149,197,257,227,191,199,367,

%T 331,149,311,127,241,179,443,307,281,331,211,127,331,233,277,563,509,

%U 521,307,397,761,577,809,733,577,857,929,941,673,787,1103,257,733,691,877

%N a(1)=2, a(n+1) is the smallest prime > n*(sum of decimal digits of a(n)).

%e a(1)=2;

%e a(2)=3 > 2 = 1*2;

%e a(3)=7 > 6 = 2*3;

%e a(4)=23 > 21 = 3*7;

%e a(5)=23 > 20 = 4*(2+3);

%e a(6)=29 > 25 = 5*(2+3);

%e a(7)=67 > 66 = 6*(2+9);

%e a(8)=97 > 91 = 7*(6+7);

%e a(9)=131 > 128 = 8*(9+7);

%e a(10)=47 > 45 = 9*(1+3+1).

%p A007953 := proc(n) add(d,d=convert(n,base,10)) ; end proc: A158054 := proc() option remember; if n = 1 then 2; else (n-1)*A007953(procname(n-1)) ; nextprime(%) ; end if; end proc: seq(A158054(n),n=1..120) ; # _R. J. Mathar_, May 19 2010

%Y Cf. A000027, A000040, A156615.

%K nonn,base,easy

%O 1,1

%A _Juri-Stepan Gerasimov_, Mar 12 2009

%E Corrected (193 replaced by 199, all terms from a(32) on replaced) by _R. J. Mathar_, May 19 2010

%E Edited by _Jon E. Schoenfield_, Feb 17 2019