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 A224977 n^2 minus sum of digits of n^2. 1
 0, 0, 0, 0, 9, 18, 27, 36, 54, 72, 99, 117, 135, 153, 180, 216, 243, 270, 315, 351, 396, 432, 468, 513, 558, 612, 657, 711, 765, 828, 891, 945, 1017, 1071, 1143, 1215, 1278, 1350, 1431, 1512, 1593, 1665, 1746, 1827, 1917, 2016, 2106, 2196, 2295, 2394, 2493 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,5 COMMENTS a(n) mod 9 = 0 for all n. LINKS Christian N. K. Anderson, Table of n, a(n) for n = 0..9999 Christian N. K. Anderson, Ulam spiral of a(n) in red, with other multiples of 9 in gray. FORMULA a(n) = A000290(n) - A004159(n). EXAMPLE a(0) = 0^2 - 0 = 0. a(12) = 144 - (1+4+4) = 135. MATHEMATICA Table[n^2 - Sum[DigitCount[n^2][[i]]i, {i, 9}], {n, 50}] (* Alonso del Arte, Apr 21 2013 *) #^2-Total[IntegerDigits[#^2]]&/@Range[0, 50] (* Harvey P. Dale, May 10 2017 *) PROG (R) library(gmp); digsum<-function(x) sum(as.numeric(unlist(strsplit(as.character(x), split="")))) ans=rep(0, 100); n=0 while(n<=100) ans[(n=n+1)]=n^2-digsum(n^2); ans CROSSREFS Cf. A067552. Derived from A000290 and A004159. Sequence in context: A206905 A083497 A067552 * A195085 A329640 A052489 Adjacent sequences: A224974 A224975 A224976 * A224978 A224979 A224980 KEYWORD nonn,base,easy AUTHOR Kevin L. Schwartz and Christian N. K. Anderson, Apr 21 2013 STATUS approved

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Last modified April 15 18:27 EDT 2024. Contains 371696 sequences. (Running on oeis4.)