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

1,1

Links

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

Example

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

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 *)

Crossrefs

Cf. A002808.

Sequence in context: A337163 A157496 A096768 * A165932 A190588 A072041

Adjacent sequences: A157526 A157527 A157528 * A157530 A157531 A157532

Keyword

base,nonn

Author

Parthasarathy Nambi, Mar 02 2009

Extensions

Corrected and extended by Emeric Deutsch, Mar 07 2009

Status

approved