cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-10 of 13 results. Next

A061910 Positive numbers k such that sum of digits of k^2 is a square.

Original entry on oeis.org

1, 2, 3, 6, 9, 10, 11, 12, 13, 14, 15, 18, 20, 21, 22, 23, 30, 31, 39, 41, 45, 48, 51, 58, 59, 60, 67, 68, 76, 77, 85, 86, 90, 94, 95, 100, 101, 102, 103, 104, 105, 110, 111, 112, 113, 120, 121, 122, 130, 131, 139, 140, 148, 150, 157, 158, 166, 175, 176, 180, 184, 185
Offset: 1

Views

Author

Asher Auel, May 17 2001

Keywords

Examples

			6^2 = 36 and 3+6 = 9 is a square. 13^2 = 169 and 1+6+9 = 16 is a square.
		

Crossrefs

Sequence A293832 gives the start of the first run of n consecutive values.

Programs

  • Magma
    [ n: n in [1..185] | IsSquare(&+Intseq(n^2)) ];  // Bruno Berselli, Jul 29 2011
    
  • Maple
    readlib(issqr): f := []: for n from 1 to 200 do if issqr(convert(convert(n^2,base,10),`+`)) then f := [op(f), n] fi; od; f;
  • Mathematica
    Select[Range[185], IntegerQ[Sqrt[Total[IntegerDigits[#^2]]]] &] (* Jayanta Basu, May 06 2013 *)
  • PARI
    is(n)=n=eval(Vec(Str(n^2)));issquare(sum(i=1,#n,n[i])) \\ Charles R Greathouse IV, Jul 29 2011
    
  • PARI
    select( is_A061910(n)=issquare(sumdigits(n^2)), [0..199]) \\ Includes the initial 0. - M. F. Hasler, Oct 16 2017
    
  • Python
    from gmpy2 import is_square
    A061910 = [n for n in range(1,10**3) if is_square(sum(int(d) for d in str(n*n)))] # Chai Wah Wu, Sep 03 2014

A028839 Sum of digits of n is a square.

Original entry on oeis.org

1, 4, 9, 10, 13, 18, 22, 27, 31, 36, 40, 45, 54, 63, 72, 79, 81, 88, 90, 97, 100, 103, 108, 112, 117, 121, 126, 130, 135, 144, 153, 162, 169, 171, 178, 180, 187, 196, 202, 207, 211, 216, 220, 225, 234, 243, 252, 259, 261, 268, 270, 277, 286, 295, 301, 306, 310
Offset: 1

Views

Author

Keywords

Comments

Difference between two consecutive terms is never equal to 8. - Carmine Suriano, Mar 31 2014
In this sequence, there is no number of the form 3*k-1. In other words, if a(n) is not divisible by 9, it must be of the form 3*k+1. - Altug Alkan, Apr 08 2016

Examples

			234511 belongs to the sequence as its sum of digits is 16, a square.
		

Crossrefs

Cf. A053057 (squares whose digit sum is also a square).

Programs

  • Magma
    [n: n in [1..400] | IsSquare(&+Intseq(n))];  // Bruno Berselli, May 26 2011
    
  • Mathematica
    Select[ Range[ 500 ], IntegerQ[ Sqrt[ Apply[ Plus, IntegerDigits[ # ] ] ] ]& ]
  • PARI
    isok(n) = issquare(sumdigits(n)); \\ Michel Marcus, Oct 30 2014

Extensions

More terms from Erich Friedman

A061267 Squares whose sum of digits as well as product of digits is a nonzero square.

Original entry on oeis.org

1, 4, 9, 144, 441, 14884, 44944, 48841, 132496, 214369, 268324, 288369, 294849, 346921, 436921, 511225, 617796, 938961, 1234321, 1336336, 1833316, 2325625, 2356225, 2585664, 2614689, 2778889, 2862864, 3323329, 3767481, 4691556
Offset: 1

Views

Author

Amarnath Murthy, Apr 24 2001

Keywords

Comments

The squares of 969, 9669, 96669, 966669, ... with n 6s belong to this sequence if n = 4*m^2 - 3. The sum of the digits of this number is 36*m^2 and the product of the digits is 108^2 * 20^k, where k = 4xm^2.

Examples

			14884 = 122^2 is a member of this sequence as 1+4+8+8+4 = 25 = 5^2 and 1*4*8*8*4 = 1024 = 32^2.
		

References

  • Amarnath Murthy, Infinitely many common members of Smarandache Additive as well as Multiplicative Square sequence, (to be published in the Smarandache Notions Journal)
  • Felice Russo, A set of new Smarandache functions, sequences and conjectures in number theory, American Research Press 2000

Crossrefs

Intersection of A050626, A028839, and A000290.
A061869 allows values with zero product.

Programs

  • Mathematica
    d[n_]:=IntegerDigits[n]; iQ[n_]:=IntegerQ[Sqrt[n]]; Select[Range[2500]^2,iQ[Plus@@(x=d[#])] && iQ[Times@@x] && FreeQ[x,0] &] (* Jayanta Basu, May 19 2013 *)
  • PARI
    is(n)=my(v=digits(n),pr=prod(i=1,#v,v[i])); pr && issquare(pr) && issquare(n) && issquare(sumdigits(n)) \\ Charles R Greathouse IV, May 19 2013

Extensions

More terms from Larry Reeves (larryr(AT)acm.org), May 11 2001

A061268 Numbers k such that k^2 has property that the sum of its digits and the product of its digits are nonzero squares.

Original entry on oeis.org

1, 2, 3, 12, 21, 122, 212, 221, 364, 463, 518, 537, 543, 589, 661, 715, 786, 969, 1111, 1156, 1354, 1525, 1535, 1608, 1617, 1667, 1692, 1823, 1941, 2166, 2235, 2337, 2379, 2515, 2943, 2963, 3371, 3438, 3631, 3828, 4018, 4077, 4119, 4271, 4338, 4341, 4471
Offset: 1

Views

Author

Amarnath Murthy, Apr 24 2001

Keywords

Comments

See A061267 for the corresponding squares (the so-called ultrasquares). - M. F. Hasler, Oct 25 2022

Examples

			212^2 = 44944, 4+4+9+4+4 = 25 = 5^2 and 4*4*9*4*4 = 2304 = 48^2.
		

References

  • Amarnath Murthy, Infinitely many common members of the Smarandache Additive as well as multiplicative square sequence, (To be published in Smarandache Notions Journal).
  • Felice Russo, A set of new Smarandache functions, sequences and conjectures in number theory, American Research Press 2000

Crossrefs

Cf. A061267 (the corresponding squares), A053057 (squares with square digit sum), A053059 (squares with square product of digits).
Sequence A061868 allows digit products = 0.

Programs

  • PARI
    select( {is_A061268(n)=vecmin(n=digits(n^2))&&issquare(vecprod(n))&&issquare(vecsum(n))}, [1..4567]) \\ M. F. Hasler, Oct 25 2022

Extensions

More terms from Larry Reeves (larryr(AT)acm.org), May 11 2001

A061269 Squares with nonzero digits such that (1) each digit is a square and (2) the sum of the digits is a square.

Original entry on oeis.org

1, 4, 9, 144, 441, 44944
Offset: 1

Views

Author

Amarnath Murthy, Apr 24 2001

Keywords

Comments

Note that (1) implies that the product of the digits is a square.
Next term, if it exists, is > 90000000000. - Larry Reeves (larryr(AT)acm.org), May 11 2001

Examples

			For example, 44944 = 212^2, each digit is a square, sum of digits = 4+4+9+4+4 = 25 = 5^2.
		

References

  • Amarnath Murthy, The Smarandache multiplicative square sequence is infinite, (to be published in Smarandache Notions Journal).
  • Amarnath Murthy, Infinitely many common members of the Smarandache additive as well as multiplicative square sequence, (to be published in Smarandache Notions Journal).

Crossrefs

If zeros are allowed as digits, the result is A061270.
A subsequence of A006716.

Programs

  • Mathematica
    For[n = 1, n < 100000, n++, a := DigitCount[n^2]; If[a[[2]] == 0, If[a[[3]] == 0, If[a[[5]] == 0, If[a[[6]] == 0, If[a[[7]] == 0, If[a[[8]] == 0, If[a[[10]] == 0, If[Sqrt[Sum[a[[i]]*i, {i, 1, 10}]] == Floor[Sqrt[Sum[a[[i]]*i, {i, 1, 10}]]], Print[n^2]]]]]]]]]] (* Stefan Steinerberger, Mar 15 2006 *)

Extensions

Edited by N. J. A. Sloane at the suggestion of Andrew S. Plewe, Jun 05 2007

A061090 Squares the sum of the squares of whose digits are squares.

Original entry on oeis.org

1, 4, 9, 100, 400, 676, 841, 900, 1444, 4225, 10000, 24025, 40000, 42025, 42436, 43264, 66049, 67600, 84100, 90000, 109561, 119716, 144400, 155236, 239121, 244036, 248004, 252004, 335241, 355216, 362404, 373321, 422500, 643204, 664225
Offset: 1

Views

Author

Amarnath Murthy, Apr 19 2001

Keywords

Comments

Contains 10^(2k) for all k.
More generally, if k is in this sequence so is 100k. - Charles R Greathouse IV, Sep 20 2012

Examples

			676 = 26^2, 6^2 + 7^2 + 6^2 = 121 = 11^2;
1444 = 38^2, 1^2 + 4^2 + 4^2 + 4^2 = 49 = 7^2.
		

References

  • A. Murthy, Smarandache Pythagoras additive square sequence (to be published in Smarandache Notions Journal).

Crossrefs

Cf. A053057.

Programs

  • Maple
    readlib(issqr): for n from 1 to 2000 do L1 := convert(n^2, base, 10): if issqr(sum(L1[i]^2, i=1..nops(L1))) then printf(`%d,`,n^2) fi: od:
  • Mathematica
    Select[Range[1000]^2,IntegerQ[Sqrt[Total[IntegerDigits[#]^2]]]&] (* Harvey P. Dale, Apr 26 2025 *)
  • PARI
    ssd(n)=n=digits(n);sum(i=1,#n,n[i]^2)
    v=List();for(n=1,1e4,if(issquare(ssd(n^2)),listput(v,n^2))); Vec(v) \\ Charles R Greathouse IV, Sep 20 2012

Extensions

Corrected and extended by James Sellers, Apr 20 2001

A061270 Squares such that each digit is a square and the sum of the digits is a square.

Original entry on oeis.org

0, 1, 4, 9, 100, 144, 400, 441, 900, 10000, 10404, 14400, 40000, 40401, 44100, 44944, 90000, 1000000, 1004004, 1040400, 1440000, 4000000, 4004001, 4040100, 4410000, 4494400, 9000000, 9941409, 11909401, 100000000, 100040004, 100400400
Offset: 1

Views

Author

Amarnath Murthy, Apr 24 2001

Keywords

Examples

			44944 = 212^2, each digit is a square, sum of digits = 4 + 4 + 9 + 4 + 4 = 25 = 5^2.
		

References

  • Amarnath Murthy, Smarandache Additive square sequence is infinite. (To be published in Smarandache Notions Journal.)
  • Amarnath Murthy, Infinitely many common members of the Smarandache Additive as well as multiplicative square sequence. (To be published in Smarandache Notions Journal.)
  • Felice Russo, A set of new Smarandache functions, sequences and conjectures in number theory, American Research Press 2000.

Crossrefs

Extensions

More terms from Larry Reeves (larryr(AT)acm.org), May 11 2001
a(1)=0 inserted by Sean A. Irvine, Jan 29 2023

A180737 a(n) is the largest n-digit square whose sum of digits is also a square.

Original entry on oeis.org

9, 81, 961, 9025, 96721, 990025, 9966649, 99980001, 999761161, 9999400009, 99998250625, 999946000729, 9999989500176, 99999960000004, 999999455981824, 9999998600000049, 99999998724439696, 999999998000000001
Offset: 1

Views

Author

Daniel Mondot, Oct 08 2010

Keywords

Crossrefs

Programs

  • Mathematica
    lnds[n_]:=Module[{s=Floor[Sqrt[10^n-1]]},While[!IntegerQ[Sqrt[Total[ IntegerDigits[ s^2]]]],s--];s^2]; Array[lnds,20] (* Harvey P. Dale, Mar 28 2013 *)

A371004 Fourth powers whose digital sum is also a fourth power.

Original entry on oeis.org

0, 1, 10000, 14641, 100000000, 104060401, 146410000, 1000000000000, 1004006004001, 1040604010000, 1464100000000, 4228599998736, 8670998958336, 9748688599521, 9948826238976, 12598637895936, 19226786746896, 19896452775936, 20699669996721, 23768199069696, 26599197668481
Offset: 1

Views

Author

Stefano Spezia, Mar 08 2024

Keywords

Comments

Among the terms of this sequence, there are:
the numbers of the form 10^(4*k) with k >= 0;
the numbers of the form (10^i + 10^j)^4 with i > j >= 0.

Crossrefs

Programs

  • Mathematica
    Select[Range[0,2500]^4, IntegerQ[DigitSum[#]^(1/4)]&]

Formula

a(n) = A371047(n)^4.

A061272 Squares such that (1) each digit is a square, (2) the sum of squares of the digits is a square.

Original entry on oeis.org

0, 1, 4, 9, 100, 400, 900, 1444, 10000, 40000, 90000, 144400, 1000000, 4000000, 9000000, 14440000, 94109401, 100000000, 400000000, 900000000, 1444000000, 9410940100, 10000000000, 10100049001, 40000000000, 90000000000, 144400000000, 414441100441, 941094010000
Offset: 1

Views

Author

Amarnath Murthy, Apr 24 2001

Keywords

Examples

			1444 = 38^2, each digit is a square, Sum of the squares of digits = 1+16+16+16 = 49 = 7^2.
		

References

  • Amarnath Murthy, Smarandache Pythagoras Additive Square Sequence. (To be published in Smarandache Notions Journal).

Crossrefs

Programs

  • Mathematica
    okQ[n_]:=Module[{fd=FromDigits[n]},IntegerQ[Sqrt[fd]]&&IntegerQ[ Sqrt[ Total[n^2]]]]; FromDigits/@Select[Tuples[{0,1,4,9},8],okQ] (* Harvey P. Dale, May 12 2011 *)

Extensions

Corrected and extended by Harvey P. Dale, May 12 2011
More terms from Jason Yuen, Aug 27 2025
Showing 1-10 of 13 results. Next