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 A082944 a(n) = concatenate(n, A010888(2*n), reverse(n)), where A010888 = digital root. 1
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 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 REFERENCES Amarnath Murthy LINKS Table of n, a(n) for n=1..30. EXAMPLE 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. 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 *) PROG (PARI) A082944(n)=fromdigits(concat([digits(n), (2*n-1)%9+1, Vecrev(digits(n))])) \\ Cf. A010888. - R. J. Cano, Jan 05 2022 CROSSREFS Cf. A010888 (digital root), A004086 (read n backwards: trailing zeros are lost - but not in this sequence here). Sequence in context: A119378 A261618 A084998 * A131973 A045571 A088285 Adjacent sequences: A082941 A082942 A082943 * A082945 A082946 A082947 KEYWORD easy,nonn,base AUTHOR Meenakshi Srikanth (menakan_s(AT)yahoo.com), May 06 2003 EXTENSIONS Definition, comment and example corrected by M. F. Hasler, Jan 05 2022 STATUS approved

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Last modified December 3 22:01 EST 2023. Contains 367540 sequences. (Running on oeis4.)