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

Author

Michel Marcus, Sep 15 2015

Keywords

• nonn
• base

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).

Examples

			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.
		

Links

• Michel Marcus, Table of n, a(n) for n = 1..1274
• Didier Müller, Somme des premiers entiers inversés, Défi Turing (in French).

Crossrefs

Cf. A000217, A062918.

Programs

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

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 *)

PARI

isok(n) = n*(n+1)/2 - sum(k=1,n, eval(concat(Vecrev(Str(k))))) > 0;