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 1-8 of 8 results.

A316481 Squares whose arithmetic mean of digits is 1 (i.e., the sum of digits equals the number of digits).

Original entry on oeis.org

1, 1100401, 2220100, 100040004, 100100025, 100220121, 100400400, 101002500, 102030201, 102212100, 103002201, 104040000, 110250000, 121022001, 121220100, 123210000, 132020100, 144000000, 210221001, 225000000, 310112100, 324000000, 400040001, 400400100
Offset: 1

Views

Author

Jon E. Schoenfield, Jul 04 2018

Keywords

Comments

Each term's number of digits is in A056991 (Numbers with digital root 1, 4, 7, or 9). For every term k in A056991, this sequence contains at least one k-digit term, with the exception of k=4. (See A316480.)

Examples

			1049^2 = 1100401, a 7-digit number whose digit sum is 1+1+0+0+4+0+1 = 7, so 1100401 is a term.
		

Crossrefs

Intersection of A000290 and A061384. - Michel Marcus, Jul 06 2018

A316484 Squares whose arithmetic mean of digits is 4 (i.e., the sum of digits is 4 times the number of digits).

Original entry on oeis.org

4, 1681, 3364, 3481, 4624, 7225, 9025, 1054729, 1069156, 1073296, 1149184, 1168561, 1183744, 1227664, 1263376, 1288225, 1308736, 1329409, 1366561, 1517824, 1522756, 1545049, 1567504, 1585081, 1607824, 1630729, 1635841, 1677025, 1682209, 1705636, 1729225
Offset: 1

Views

Author

Jon E. Schoenfield, Jul 04 2018

Keywords

Comments

Each term's number of digits is in A056991 (Numbers with digital root 1, 4, 7, or 9). For every term k in A056991, this sequence contains at least one k-digit term. (See A316480.)

Examples

			1027^2 + 1054729, a 7-digit number whose digit sum is 1+0+5+4+7+2+9 = 28 = 4*7, so 1054729 is a term.
10044^2 = 100881936, a 9-digit number whose digit sum is 1+0+0+8+8+1+9+3+6 = 36 = 4*9, so 100881936 is a term.
		

Crossrefs

Programs

  • Maple
    f:= proc(n) local L;
      L:= convert(n^2,base,10);
      if convert(L,`+`)=4*nops(L) then n^2 fi
    end proc:
    map(f, [$1..2000]); # Robert Israel, Jul 05 2018
  • Mathematica
    Select[Range[1500]^2, Mean[IntegerDigits[#]] == 4 &] (* Giovanni Resta, Jul 05 2018 *)
  • PARI
    isok(n) = (n>0) && issquare(n) && (sumdigits(n) == 4*#digits(n)); \\ Michel Marcus, Jul 05 2018

A316488 Squares whose arithmetic mean of digits is 8 (i.e., the sum of digits is 8 times the number of digits).

Original entry on oeis.org

97969, 88998998929, 97888999968769, 38999699989995889, 79949788888999969, 98987998979757889, 99497897999899876, 498999778899898896, 597998978979699969, 799778987996998689, 896899597989995889, 899984989899599769, 979978999994798769, 989999999787828969
Offset: 1

Views

Author

Jon E. Schoenfield, Jul 04 2018

Keywords

Comments

Each term's number of digits is in A174438 (Numbers that are congruent to {0, 2, 5, 8} mod 9). For every positive term k in A174438, it appears that this sequence contains at least one k-digit term with the exception of k=2, k=8, and k=9. (See A316480.)

Examples

			313^2 = 97969, a 5-digit number whose digit sum is 9+7+9+6+9 = 40 = 8*5, so 97969 is a term.
9949823114^2 = 98998979999888656996, a 20-digit number whose digit sum is 9+8+9+9+8+9+7+9+9+9+9+8+8+8+6+5+6+9+9+6 = 160 = 8*20, so 98998979999888656996 is a term.
		

Crossrefs

Intersection of A000290 and A061425. - Michel Marcus, Jul 06 2018

A316482 Squares whose arithmetic mean of digits is 2 (i.e., the sum of digits is twice the number of digits).

Original entry on oeis.org

21025, 23104, 32041, 36100, 63001, 10125124, 10176100, 10233601, 10530025, 10824100, 11122225, 11303044, 11424400, 12040900, 12103441, 12222016, 12602500, 13315201, 13322500, 14055001, 14600041, 16008001, 16080100, 16810000, 20205025, 20214016, 20611600
Offset: 1

Views

Author

Jon E. Schoenfield, Jul 04 2018

Keywords

Comments

Each term's number of digits is in A174438 (Numbers that are congruent to {0, 2, 5, 8} mod 9). For every positive term k in A174438, this sequence contains at least one k-digit term, with the exception of k=2. (See A316480.)

Examples

			145^2 = 21025, a 5-digit number whose digit sum is 2+1+0+2+5 = 10 = 2*5, so 21025 is a term.
		

Crossrefs

Intersection of A000290 and A061385. - Michel Marcus, Jul 06 2018

A316483 Squares whose arithmetic mean of digits is 3 (i.e., the sum of digits is 3 times the number of digits).

Original entry on oeis.org

144, 225, 324, 441, 900, 108900, 114921, 119025, 125316, 129600, 136161, 140625, 145161, 159201, 161604, 164025, 176400, 184041, 205209, 210681, 213444, 216225, 219024, 221841, 239121, 242064, 245025, 248004, 254016, 291600, 304704, 308025, 311364, 314721
Offset: 1

Views

Author

Jon E. Schoenfield, Jul 04 2018

Keywords

Comments

Each term's number of digits is divisible by 3. (See A316480.)

Examples

			12^2 = 144, a 3-digit number whose digit sum is 1+4+4 = 9 = 3*3, so 144 is a term.
360^2 = 129600, a 6-digit number whose digit sum is 1+2+9+6+0+0 = 18 = 3*6, so 129600 is a term.
		

Crossrefs

Intersection of A000290 and A061386. - Michel Marcus, Jul 06 2018

A316485 Squares whose arithmetic mean of digits is 5 (i.e., the sum of digits is 5 times the number of digits).

Original entry on oeis.org

64, 12769, 14884, 24649, 24964, 27556, 30976, 33856, 37249, 37636, 44944, 48841, 56644, 65536, 66049, 70756, 75076, 75625, 80089, 80656, 85264, 96721, 10778089, 10982596, 11464996, 11498881, 11648569, 11957764, 11992369, 12369289, 12559936, 12687844, 12909649
Offset: 1

Views

Author

Jon E. Schoenfield, Jul 04 2018

Keywords

Comments

Each term's number of digits is in A174438 (Numbers that are congruent to {0, 2, 5, 8} mod 9). For every positive term k in A174438, this sequence contains at least one k-digit term. (See A316480.)

Examples

			8^2 = 64, a 2-digit number whose digit sum is 6+4 = 10 = 5*2, so 64 is a term.
3283^2 = 10778089, an 8-digit number whose digit sum is 1+0+7+7+8+0+8+9 = 40 = 5*8, so 10778089 is a term.
		

Crossrefs

Intersection of A000290 and A061388. - Michel Marcus, Jul 06 2018

Programs

  • Mathematica
    Select[Range[4000]^2,Mean[IntegerDigits[#]]==5&] (* Harvey P. Dale, Sep 10 2022 *)

A316486 Squares whose arithmetic mean of digits is 6 (i.e., the sum of digits is 6 times the number of digits).

Original entry on oeis.org

576, 729, 149769, 173889, 178929, 199809, 278784, 288369, 294849, 389376, 439569, 459684, 467856, 471969, 509796, 589824, 599076, 617796, 660969, 665856, 675684, 685584, 695556, 746496, 751689, 767376, 777924, 788544, 793881, 799236, 853776, 859329, 870489
Offset: 1

Views

Author

Jon E. Schoenfield, Jul 04 2018

Keywords

Comments

Each term's number of digits is divisible by 3. (See A316480.)

Examples

			24^2 = 576, a 3-digit number whose digit sum is 5+7+6 = 18 = 6*3, so 576 is a term.
10386^2 = 107868996, a 9-digit number whose digit sum is 1+0+7+8+6+8+9+9+6 = 54 = 6*9, so 107868996 is a term.
		

Crossrefs

Intersection of A000290 and A061423. - Michel Marcus, Jul 06 2018

Programs

  • Mathematica
    Select[Range[1000]^2,Mean[IntegerDigits[#]]==6&] (* Harvey P. Dale, Aug 05 2021 *)

A316487 Squares whose arithmetic mean of digits is 7 (i.e., the sum of digits is 7 times the number of digits).

Original entry on oeis.org

2778889, 4695889, 5678689, 5697769, 5938969, 6568969, 6589489, 6848689, 6895876, 7974976, 7997584, 8779369, 9878449, 9966649, 299739969, 377796969, 396686889, 458687889, 467986689, 487658889, 488984769, 496977849, 538889796, 557998884, 559984896, 569967876
Offset: 1

Views

Author

Jon E. Schoenfield, Jul 04 2018

Keywords

Comments

Each term's number of digits is in A056991 (Numbers with digital root 1, 4, 7, or 9). For every term k in A056991, this sequence contains at least one k-digit term, with the exception of k=1 and k=4. (See A316480.)

Examples

			17313^2 = 299739969, a 9-digit number whose digit sum is 2+9+9+7+3+9+9+6+9 = 63 = 7*9, so 299739969 is a term.
43474^2 = 1889988676, a 10-digit number whose digit sum is 1+8+8+9+9+8+8+6+7+6 = 70 = 7*10, so 1889988676 is a term.
		

Crossrefs

Intersection of A000290 and A061424. - Michel Marcus, Jul 06 2018
Showing 1-8 of 8 results.