A088133 Sum of first and last digits of n. Different from A115299.

0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 8, 9, 10, 11, 12, 13, 14

Offset: 0

Author

Zak Seidov, Sep 20 2003

Keywords

• easy
• nonn
• base

Crossrefs

Cf. A000030 (first digit of n), A010879 (last digit of n).

Cf. A046704, A007953, A088134, A088135, A088136.

Programs

Mathematica

Total[{First[IntegerDigits[#]],Last[IntegerDigits[#]]}]&/@Range[90] (* Harvey P. Dale, Aug 21 2018 *)

PARI

apply( {A088133(n)=n\10^logint(n+!n, 10)+n%10}, [0..99]) \\ M. F. Hasler, Apr 22 2024

Python

list(map(A088133 := lambda n: int(str(n)[0])+n%10, range(99))) # M. F. Hasler, Apr 22 2024

Formula

a(n) = A000030(n) + A010879(n). - M. F. Hasler, Apr 22 2024

Extensions

Extended to a(0) = 0 by M. F. Hasler, Apr 22 2024