A154544 Primes p such that the smallest digit of p + the number of smallest digits of p is an even composite number.

3, 5, 7, 37, 43, 53, 59, 73, 79, 83, 97, 223, 227, 229, 347, 349, 359, 367, 379, 389, 397, 439, 443, 449, 463, 563, 569, 577, 587, 593, 599, 643, 653, 659, 673, 683, 739, 743, 757, 773, 839, 853, 857, 859, 863, 883, 887, 937, 953, 983, 997, 1117, 1151, 1171

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

3 is the smallest digit of 37 and it appears once; 3+1 is an even composite so 37 appears in this sequence.

Maple

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:
A054054 := proc(n) min(op(convert(n, base, 10)) ) ; end proc:
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

Mathematica

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 *)

Crossrefs

Sequence in context: A067232 A327413 A106115 * A155034 A126359 A182373

Adjacent sequences: A154541 A154542 A154543 * A154545 A154546 A154547

Keyword

nonn,base,less

Author

Juri-Stepan Gerasimov, Jan 11 2009

Extensions

Corrected (83, 443, 463 inserted) by R. J. Mathar, May 05 2010

Status

approved