A062918 Sum of the digit reversals of the first n natural numbers.

1, 3, 6, 10, 15, 21, 28, 36, 45, 46, 57, 78, 109, 150, 201, 262, 333, 414, 505, 507, 519, 541, 573, 615, 667, 729, 801, 883, 975, 978, 991, 1014, 1047, 1090, 1143, 1206, 1279, 1362, 1455, 1459, 1473, 1497, 1531, 1575, 1629, 1693, 1767, 1851, 1945, 1950, 1965

Offset: 1

Author

Amarnath Murthy, Jul 02 2001

Keywords

• nonn
• base
• easy

Comments

a(n) = A000217(n) for n=1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 86, 89, ...; checked up to 10^7. - Michel Marcus, Sep 15 2015; checked up to 2^32 ~ 4*10^9. - Kenny Lau, Aug 01 2017

Examples

			a(12) = 78 as 1+2+3+4+5+6+7+8+9+R(10)+R(11)+R(12) = 1+2+3+4+5+6+7+8+9+01+11+21 = 78.
		

Links

• Harry J. Smith, Table of n, a(n) for n=1..1000

Crossrefs

Cf. A000217, A004086, A069792.

Programs

Mathematica

Accumulate[Table[FromDigits[Reverse[IntegerDigits[n]]],{n,1,120}]] (* Enrique Pérez Herrero, Jun 01 2013 *)
Accumulate[IntegerReverse[Range[60]]] (* Harvey P. Dale, Dec 25 2021 *)

PARI

{ a=0; for (n=1, 1000, x=n; r=0; while (x>0, d=x-10*(x\10); x\=10; r=r*10 + d); write("b062918.txt", n, " ", a+=r) ) } \\ Harry J. Smith, Aug 12 2009

PARI

a(n) = sum(k=1,n, eval(concat(Vecrev(Str(k))))); \\ Michel Marcus, Sep 15 2015

Extensions

More terms from Larry Reeves (larryr(AT)acm.org), Jul 05 2001