A144591 Composites of the form smallest digit of n + prime(n).

8, 16, 24, 27, 32, 32, 38, 42, 44, 48, 54, 60, 62, 68, 74, 81, 85, 91, 99, 105, 111, 128, 133, 140, 142, 152, 154, 160, 166, 170, 180, 183, 194, 201, 203, 215, 231, 234, 244, 255, 262, 268, 274, 276, 282, 284, 295, 310, 315, 318, 323, 343, 354, 361, 370, 377

Offset

1,1

Links

Table of n, a(n) for n=1..56.

Example

Prime(1) = 2 and 1 + 2 = 3 (prime);
prime(2) = 3 and 2 + 3 = 5 (prime);
prime(3) = 5 and 3 + 5 = 8 (composite), so a(1) = 8;
prime(4) = 7 and 4 + 7 = 11 (prime);
prime(5) = 11 and 5 + 11 = 16 (composite), so a(2) = 16; etc.

Maple

A054054 := proc(n) min(op(convert(n, base, 10)) ) ; end proc: A144591 := proc(n) p := ithprime(n) ; sd := A054054(n) ; if not isprime(p+sd) then printf("%d, ", p+sd) ; end if; end proc: seq(A144591(n), n=1..400) ; # R. J. Mathar, May 01 2010

Mathematica

Select[Table[Prime[n]+Min[IntegerDigits[n]], {n, 80}], CompositeQ] (* The program uses the CompositeQ function from Mathematica version 10 *) (* Harvey P. Dale, Nov 15 2015 *)

Crossrefs

Cf. A000040, A002808.

Sequence in context: A325261 A333195 A229972 * A078131 A122612 A078130

Adjacent sequences: A144588 A144589 A144590 * A144592 A144593 A144594

Keyword

nonn,base

Author

Juri-Stepan Gerasimov, Jan 12 2009

Extensions

Corrected (369 replaced by 370) by R. J. Mathar, May 01 2010

Status

approved