A061513 a(0) = 0; a(n) is obtained by incrementing each digit of a(n-1) by 2.

0, 2, 4, 6, 8, 10, 32, 54, 76, 98, 1110, 3332, 5554, 7776, 9998, 11111110, 33333332, 55555554, 77777776, 99999998, 1111111111111110, 3333333333333332, 5555555555555554, 7777777777777776, 9999999999999998, 11111111111111111111111111111110, 33333333333333333333333333333332

Offset

0,2

Comments

In A061511-A061522, A061746-A061750 when the incremented digit exceeds 9 it is written as a 2-digit string. So 9+1 becomes the 2-digit string 10, etc.

Every term > 8 is made up of only two different consecutive digits, the smaller of which occurs only as the least significant digit.

Otherwise said, these are one less than the odd repdigits (A010785) of length 2^k, cf. formula. - M. F. Hasler, Jun 24 2016

Links

Table of n, a(n) for n=0..26.

Formula

a(n) = A061512(n)-1 = (10^2^floor(n/5)-1)/9*(n%5*2+1) - 1, where n%5 means the remainder (in {0..4}) of n divided by 5. - M. F. Hasler, Jun 24 2016

Example

Following 32; 3+2 = 5 and 2+2 = 4, hence the next term is 54.

Mathematica

NestList[FromDigits[Flatten[IntegerDigits/@(IntegerDigits[#]+2)]]&, 0, 30] (* Harvey P. Dale, Jul 07 2012 *)

Prog

(PARI) A061513(n)=10^2^(n\5)\9*(n%5*2+1)-1 \\ M. F. Hasler, Jun 24 2016

Crossrefs

Cf. A061511 - A061522, A061746 - A061750; A061581 - A061587.

Sequence in context: A229363 A083498 A172442 * A134244 A195874 A195873

Adjacent sequences: A061510 A061511 A061512 * A061514 A061515 A061516

Keyword

base,nonn

Author

Amarnath Murthy, May 08 2001

Extensions

More terms from Larry Reeves (larryr(AT)acm.org), May 11 2001

Status

approved