A362896 a(0)=2. For n>0, let d = n-th digit in the sequence thus far. a(n) = a(n-1) + d if d is even. Otherwise, a(n) = a(n-1) - d.

2, 4, 8, 16, 15, 21, 20, 15, 17, 16, 18, 18, 17, 12, 11, 4, 3, 9, 8, 16, 15, 23, 22, 15, 14, 16, 15, 14, 18, 15, 6, 14, 13, 19, 18, 13, 15, 12, 14, 16, 15, 10, 9, 13, 12, 18, 17, 12, 11, 15, 14, 22, 21, 16, 22, 21, 25, 24, 21, 20, 11, 10, 18, 17, 14, 13, 8, 7

Offset

0,1

Comments

"-" signs on negative values are ignored when determining the n-th digit.

Links

Gavin Lupo, Table of n, a(n) for n = 0..10000

Example

a(0) =  2.
a(1) =  4. 1st digit is 2, which is even. 2 + 2 = 4.
a(2) =  8. 2nd digit is 4, which is even. 4 + 4 = 8.
a(3) = 16. 3rd digit is 8, which is even. 8 + 8 = 16.
a(4) = 15. 4th digit is 1, which is odd.  16 - 1 = 15.
a(5) = 21. 5th digit is 6, which is even. 15 + 6 = 21.

Prog

(Python)
a = [2]
split = []
for i in range(100):
    split += [int(j) for j in str(abs(a[i]))]
    if split[i] % 2 == 0:
        a.append((a[i] + split[i]))
    else:
        a.append((a[i] - split[i]))
print(a)

Crossrefs

Cf. A362371, A362551.

Sequence in context: A210023 A301807 A062116 * A316749 A008381 A083780

Adjacent sequences: A362893 A362894 A362895 * A362897 A362898 A362899

Keyword

sign,easy,base

Author

Gavin Lupo, May 09 2023

Status

approved