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 A061912 a(n) is the smallest m for which sqrt(sum of digits of m^2) = n. 8
 0, 1, 2, 3, 13, 67, 264, 1667, 16667, 94863, 1643167, 29983327, 706399164, 31144643167, 1296109172867, 62441868958167, 6927459779738887, 447213595487659543, 77453069648658793167, 14104963594032775808167, 3146266035952345970972687 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS a(15) <= 62441868958167. - Donovan Johnson, Jul 10 2012 a(21) <= 29999999949999914454883190583. a(22) <= 948566760423324122079007168333. - Zhining Yang, Jun 21 2024 LINKS Table of n, a(n) for n=0..20. Mathematical Reflections, Solution to Problem J307, Issue 5, 2014, p. 1. EXAMPLE Sum of digits of 13^2 = sum of digits of 169 = 16 is the first occurrence of 4^2, so a(4) = 13. MAPLE f := []: a := 1: for i from 1 to 10 do for j from 1 do if sqrt(convert(convert(j^2, base, 10), `+`)) = i then f := [op(f), j]; a := j; break fi; od; od; f; MATHEMATICA t={}; m=0; Do[While[Sqrt[Total[IntegerDigits[m^2]]] != n, m++]; AppendTo[t, m], {n, 0, 9}]; t (* Jayanta Basu, May 06 2013 *) PROG (PARI) a(n) = my(k=0); while(sumdigits(k^2) != n^2, k++); k; \\ Michel Marcus, Jan 07 2017 CROSSREFS Cf. A007953, A004159, A061909, A061910, A061911, A067072. Cf. A067075, A286650. Sequence in context: A068945 A219698 A293251 * A212433 A013167 A224239 Adjacent sequences: A061909 A061910 A061911 * A061913 A061914 A061915 KEYWORD nonn,base,more AUTHOR Asher Auel, May 17 2001 EXTENSIONS a(11) from John W. Layman, Jan 10 2002 a(12) from Ryan Propper, Jul 07 2005 a(13) from Zak Seidov, Jan 27 2011 a(14) from Donovan Johnson, Jul 10 2012 a(15)-a(20) from Zhining Yang, Jun 21 2024 STATUS approved

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Last modified September 15 16:35 EDT 2024. Contains 375938 sequences. (Running on oeis4.)