A082944 a(n) = concatenate(n, A010888(2*n), reverse(n)), where A010888 = digital root.

121, 242, 363, 484, 515, 636, 757, 878, 999, 10201, 11411, 12621, 13831, 14141, 15351, 16561, 17771, 18981, 19291, 20402, 21612, 22822, 23132, 24342, 25552, 26762, 27972, 28282, 29492, 30603

Offset: 1

Author

Meenakshi Srikanth (menakan_s(AT)yahoo.com), May 06 2003

Keywords

• easy
• nonn
• base

Comments

The central digit A010888(2*n) cyclically repeats the nine digits (2, 4, 6, 8, 1, 3, 5, 7, 9) in this order.

The sum of the digits of n plus the digits of the reverse of n is always simply 2 times the sum of the digits of n. - Harvey P. Dale, Aug 12 2019

Examples

			For a(17): 1+7+7+1 = 16. 1+6 = 7. Thus the center digit is 7 and a(17) = 17771.
For a(23): 2+3+3+2 = 10. 1+0 = 1. Thus the center digit is 1 and a(23) = 23132.
		

References

• Amarnath Murthy

Crossrefs

Cf. A010888 (digital root), A004086 (read n backwards: trailing zeros are lost - but not in this sequence here).

Programs

Mathematica

nxt[n_]:=Module[{idn=IntegerDigits[n],b,c},b=NestWhile[Total[IntegerDigits[ # ]]&, 2 Total[idn],#>9&];c=Reverse[idn];FromDigits[Join[idn,{b},c]]]; Table[ nxt[n],{n,20}] (* Harvey P. Dale, Aug 12 2019 *)

PARI

A082944(n)=fromdigits(concat([digits(n), (2*n-1)%9+1, Vecrev(digits(n))])) \\ Cf. A010888. - R. J. Cano, Jan 05 2022

Extensions

Definition, comment and example corrected by M. F. Hasler, Jan 05 2022