Oliver Bel - cp's OEIS frontend

User: Oliver Bel

Oliver Bel has authored 2 sequences.

A239937 Numbers k such that DigitSum(k^2) > DigitSum((k+1)^2).

3, 7, 8, 9, 14, 17, 19, 24, 26, 28, 29, 31, 33, 34, 37, 38, 39, 43, 44, 47, 48, 53, 54, 57, 59, 63, 64, 67, 69, 70, 74, 77, 78, 79, 83, 84, 87, 88, 89, 93, 94, 97, 98, 99, 104, 107, 109, 114, 117, 118, 119, 122, 124, 126, 128, 129, 133, 134, 137, 138, 141, 143

Offset: 1

Oliver Bel, Mar 29 2014

			For k=3, we have DigitSum(3^2) = 9 > 7 = DigitSum(4^2).

Cf. A007953 (sum of digits of n), A004159 (sum of digits of n^2).

lis = Table[Total[IntegerDigits[n^2, 10]], {n, 1, 100}];
Flatten[Position[Greater @@@ Partition[lis, 2, 1], True]]
Position[Partition[Total[IntegerDigits[#]]&/@(Range[150]^2),2,1],?(#[[1]]> #[[2]]&),1,Heads->False]//Flatten (* _Harvey P. Dale, Feb 19 2020 *)

isok(k) = sumdigits(k^2) > sumdigits((k+1)^2); \\ Michel Marcus, Jul 03 2021

More terms from Jon E. Schoenfield, Mar 29 2014

A239935 Numbers k such that DigitSum(3^k) > DigitSum(3^(k+1)).

Original entry on oeis.org

11, 14, 15, 18, 20, 27, 29, 31, 34, 38, 41, 43, 47, 48, 50, 53, 54, 58, 59, 63, 64, 65, 67, 69, 71, 72, 75, 77, 79, 83, 88, 90, 94, 98, 99, 102, 103, 107, 109, 112, 114, 118, 119, 123, 125, 131, 132, 134, 136, 139, 141, 142, 146, 150, 154, 159, 161, 164, 167

Offset: 1

Oliver Bel, Mar 29 2014

			For k=11, we have DigitSum(3^11) = 27 > 18 = DigitSum(3^12).

Robert Israel, Table of n, a(n) for n = 1..8009

Cf. A004166, A007953.

N:= 1000: # to get the first N terms
threen:= 3:
digsum:= 3:
count:= 0:
for n from 1 while count < N do
  threen:= 3*threen;
  oldsum:= digsum;
  digsum:= convert(convert(threen,base,10),`+`);
  if oldsum > digsum then
     count:= count+1;
     A239935[count]:= n;
  fi
od: # Robert Israel, Apr 18 2014

lis = Table[Total[IntegerDigits[3^n, 10]], {n, 1, 100}];
Flatten[Position[Greater @@@ Partition[lis, 2, 1], True]]

isok(k) = sumdigits(3^k) > sumdigits(3^(k+1)); \\ Michel Marcus, Jul 03 2021

More terms from Jon E. Schoenfield, Mar 29 2014

cp's OEIS Frontend

User: Oliver Bel

A239937 Numbers k such that DigitSum(k^2) > DigitSum((k+1)^2).

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