A262229 Numbers m such that A000217(m) > A062918(m).

10, 11, 87, 88, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 895, 896, 897, 898, 899, 900, 901, 902, 903, 904, 905, 906, 907, 908, 909, 910, 911, 912, 913, 914, 915, 916, 917, 918, 919, 920, 921, 922, 923, 924, 925, 926, 927, 928, 929, 930, 931

Offset

1,1

Comments

The sum of the digit reversals of first n natural numbers (A062918) is equal to the sum of the first n natural numbers (A000217) for n=1 to 9. Then 10 is the first time that A000217(m) > A062918(m).

Links

Michel Marcus, Table of n, a(n) for n = 1..1274

Didier Müller, Somme des premiers entiers inversés, Défi Turing (in French).

Example

For m=10, 1+2+3+4+5+6+7+8+9+10 is > 1+2+3+4+5+6+7+8+9+01, so 10 is a term.

Mathematica

lim = 931; t = Rest@ Accumulate[Range[0, lim]]; s = Accumulate[Table[FromDigits[Reverse[IntegerDigits@ n]], {n, 1, lim + 1}]]; Select[Range@ lim, t[[#]] > s[[#]] &] (* Michael De Vlieger, Sep 15 2015, after Harvey P. Dale at A000217 and Enrique Pérez Herrero at A062918 *)

Prog

(PARI) isok(n) = n*(n+1)/2 - sum(k=1, n, eval(concat(Vecrev(Str(k))))) > 0;
(Magma) [m: m in [0..10^3] | m*(m+1)/2 gt &+[Seqint(Reverse(Intseq(i))): i in [0..m]]]; // Bruno Berselli, Sep 16 2015

Crossrefs

Cf. A000217, A062918.

Sequence in context: A037958 A041214 A228381 * A347182 A331604 A086457

Adjacent sequences: A262226 A262227 A262228 * A262230 A262231 A262232

Keyword

nonn,base

Author

Michel Marcus, Sep 15 2015

Status

approved