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 A230638 Smallest number m such that u + (sum of base-4 digits of u) = m has exactly n solutions. 19
 0, 17, 16385, 16777234 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Indices of records in A230632: a(n) is the index of the first n in A230632. The terms are a(1)=0, a(2)=4^2+1, a(3)=4^7+1, a(4)=4^12+17+1, a(5)=4^5368+17+1, a(6)=4^10924+16385+1, a(7)=4^5597880+16385+20. Note that a(7) breaks the pattern of the first six terms. a(8) = 4^16777229 + 4^12 + 19. For the leading power of 4 see A230637. LINKS Max Alekseyev, Table of expressions for a(n), for n=1..100 Max A. Alekseyev and N. J. A. Sloane, On Kaprekar's Junction Numbers, arXiv:2112.14365, 2021; Journal of Combinatorics and Number Theory, 2022 (to appear). EXAMPLE n=2: the two solutions to u+(base-4 digit-sum of u) = 17 are 13 and 16. n=3: the three solutions to u+(base-4 digit-sum of u) = 4^7+1 are 4^7, 4^7-15, 4^7-18. n=4: the four solutions to u+(base-4 digit-sum of u) = 4^12+17+1 are 4^12+{16, 13, -14, -17}. CROSSREFS Cf. A230637. Related base-4 sequences:  A053737, A230631, A230632, A010064, A230633, A230634, A230635, A230636, A230637, A230638, A010065 (trajectory of 1) Smallest number m such that u + (sum of base-b digits of u) = m has exactly n solutions, for bases 2 through 10: A230303, A230640, A230638, A230867, A238840, A238841, A238842, A238843, A006064. Sequence in context: A300596 A308962 A191964 * A308671 A308670 A308571 Adjacent sequences:  A230635 A230636 A230637 * A230639 A230640 A230641 KEYWORD nonn,base AUTHOR N. J. A. Sloane, Oct 31 2013 EXTENSIONS a(8) from Max Alekseyev, Oct 31 2013 STATUS approved

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Last modified September 27 13:46 EDT 2022. Contains 357062 sequences. (Running on oeis4.)