A118137 Sum of decimal digits of two successive natural numbers.

1, 3, 5, 7, 9, 11, 13, 15, 17, 10, 3, 5, 7, 9, 11, 13, 15, 17, 19, 12, 5, 7, 9, 11, 13, 15, 17, 19, 21, 14, 7, 9, 11, 13, 15, 17, 19, 21, 23, 16, 9, 11, 13, 15, 17, 19, 21, 23, 25, 18, 11, 13, 15, 17, 19, 21, 23, 25, 27, 20, 13, 15, 17, 19, 21, 23, 25, 27, 29, 22, 15, 17, 19, 21, 23

Offset

0,2

Links

Jason Jewell, Table of n, a(n) for n = 0..1000 (first 75 terms from Giovanni Teofilatto)

Formula

a(n) = A007953(n) + A007953(n+1). - Michel Marcus, Sep 06 2019

Maple

read("transforms") ;
A118137 := proc(n)
        digsum(n)+digsum(n+1) ;
end proc: # R. J. Mathar, Apr 03 2012
# second Maple program:
a:= n-> add(i, i=convert(parse(cat(n, n+1)), base, 10)):
seq(a(n), n=0..100);  # Alois P. Heinz, Sep 08 2019

Mathematica

a[n_] := Total@ Flatten@ IntegerDigits[{n, n+1}]; Array[a, 80, 0] (* Giovanni Resta, Sep 06 2019 *)

Prog

(PARI) a(n) = sumdigits(n) + sumdigits(n+1); \\ Michel Marcus, Sep 06 2019

Crossrefs

Cf. A007953.

Sequence in context: A187907 A024806 A084834 * A160931 A160924 A063280

Adjacent sequences: A118134 A118135 A118136 * A118138 A118139 A118140

Keyword

base,easy,nonn

Author

Giovanni Teofilatto, May 13 2006

Extensions

Added missing term a(18). - Jason Jewell, Sep 06 2019

Status

approved