A157529 Composite numbers whose first digit is equal to the sum of all the other digits.

22, 33, 44, 55, 66, 77, 88, 99, 110, 202, 220, 303, 312, 321, 330, 404, 413, 422, 440, 505, 514, 532, 550, 606, 615, 624, 633, 642, 651, 660, 707, 716, 725, 734, 752, 770, 808, 817, 826, 835, 844, 862, 871, 880, 909, 918, 927, 936, 945, 954, 963, 972, 981

Offset: 1

Author

Parthasarathy Nambi, Mar 02 2009

Keywords

• base
• nonn

Examples

			990 is a composite number whose first digit is equal to the sum of all the other digits.
		

Links

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

Crossrefs

Cf. A002808.

Programs

Maple

a := proc (n) local nn: nn := convert(n, base, 10): if isprime(n) = false and nn[nops(nn)] = add(nn[j], j = 1 .. nops(nn)-1) then n else end if end proc: seq(a(n), n = 2 .. 1100); # Emeric Deutsch, Mar 07 2009

Mathematica

cnfdQ[n_]:=With[{id=IntegerDigits[n]},CompositeQ[n]&&id[[1]]==Total[Rest[id]]]; Select[ Range[1000],cnfdQ] (* Harvey P. Dale, Aug 10 2024 *)

Extensions

Corrected and extended by Emeric Deutsch, Mar 07 2009