|
%I #12 Feb 10 2019 01:53:26
%S 3,5,7,37,43,53,59,73,79,83,97,223,227,229,347,349,359,367,379,389,
%T 397,439,443,449,463,563,569,577,587,593,599,643,653,659,673,683,739,
%U 743,757,773,839,853,857,859,863,883,887,937,953,983,997,1117,1151,1171
%N Primes p such that the smallest digit of p + the number of smallest digits of p is an even composite number.
%H Harvey P. Dale, <a href="/A154544/b154544.txt">Table of n, a(n) for n = 1..1000</a>
%e 3 is the smallest digit of 37 and it appears once; 3+1 is an even composite so 37 appears in this sequence.
%p frequdig := proc(n,dig) local f,d ; f := 0 ; for d in convert(n,base,10) do if d = dig then f :=f+1; end if; end do; f ; end proc:
%p A054054 := proc(n) min(op(convert(n,base,10)) ) ; end proc:
%p for n from 1 to 500 do p := ithprime(n) ; sdg := A054054(p) ; a := sdg +frequdig(p,sdg) ; if not isprime(a) and type(a,'even') then printf("%d,",p ) ; end if; end do: # _R. J. Mathar_, May 05 2010
%t nsdQ[n_]:=Module[{sd=Min[IntegerDigits[n]],t},t=sd+DigitCount[n,10,sd];t>2&&EvenQ[t]]; Select[Prime[Range[200]], nsdQ] (* _Harvey P. Dale_, Oct 17 2013 *)
%K nonn,base,less
%O 1,1
%A _Juri-Stepan Gerasimov_, Jan 11 2009
%E Corrected (83, 443, 463 inserted) by _R. J. Mathar_, May 05 2010
|
