A158203 - OEIS

A158203

Primes the sum of whose first digit and largest digit is a prime.

11, 23, 29, 47, 67, 89, 101, 163, 223, 229, 233, 239, 251, 269, 293, 383, 409, 419, 439, 449, 457, 467, 479, 491, 499, 563, 587, 607, 617, 647, 673, 677, 809, 829, 839, 859, 1021, 1061, 1063, 1163, 1201, 1361, 1423, 1433, 1601, 1613, 1621, 1663, 2003, 2029

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

Almost all terms will start with 2, 4, or 8.

Just under 69% of the first 20000 terms begin with 2, 4, or 8. - Harvey P. Dale, Jul 29 2016

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..10000

MAPLE

A054055 := proc(n) max(op(convert(n, base, 10))) ; end proc: A000030 := proc(n) op(-1, convert(n, base, 10)) ; end proc: isA158203 := proc(n) if isprime(n) then A054055(n)+A000030(n) ; isprime(%) ; else false; end if; end: for i from 1 to 2000 do if isA158203( i) then printf("%d, ", i) ; fi; od: # R. J. Mathar, Oct 22 2009

MATHEMATICA

sflQ[n_]:=Module[{idn=IntegerDigits[n]}, PrimeQ[idn[[1]]+Max[idn]]]; Select[Prime[Range[5, 500]], sflQ] (* Harvey P. Dale, Jul 29 2016 *)

CROSSREFS

Cf. A000040, A157175.

Sequence in context: A243461 A259560 A136001 * A161754 A038904 A179630

Adjacent sequences: A158200 A158201 A158202 * A158204 A158205 A158206

KEYWORD

nonn,base,easy,less

AUTHOR

Juri-Stepan Gerasimov, Mar 13 2009

STATUS

approved