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.

Previous Showing 11-19 of 19 results.

A015932 Positive integers n such that 2^n == 2^10 (mod n).

Original entry on oeis.org

1, 2, 4, 6, 7, 8, 10, 12, 16, 24, 28, 30, 32, 34, 48, 50, 64, 70, 73, 96, 110, 112, 128, 130, 150, 170, 190, 192, 230, 256, 290, 310, 330, 370, 384, 410, 430, 442, 448, 470, 512, 530, 532, 550, 590, 610, 670, 710
Offset: 1

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Author

Keywords

Comments

The odd terms are given by A215612.
For all m, 2^A033982(m)-1 belongs to this sequence.

Crossrefs

Programs

  • Mathematica
    Select[Range[1000], Mod[2^# - 2^10, #] == 0 &] (* T. D. Noe, Aug 17 2012 *)

Extensions

Edited by Max Alekseyev, Jul 30 2011

A015937 Positive integers n such that 2^n == 2^12 (mod n).

Original entry on oeis.org

1, 2, 4, 6, 8, 12, 16, 18, 20, 22, 23, 24, 32, 36, 40, 42, 48, 60, 62, 64, 68, 72, 80, 84, 89, 96, 120, 126, 128, 132, 144, 156, 160, 168, 180, 192, 204, 228, 240, 252, 256, 276, 288, 312, 320, 336, 340, 348, 352, 360, 372, 384, 420, 444, 462
Offset: 1

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Author

Keywords

Comments

The odd terms are given by A215613.
For all m, 2^A051446(m)-1 belongs to this sequence.

Crossrefs

Programs

  • Mathematica
    With[{c=2^12},Select[Range[1,6000],Divisible[2^#-c,#]&]] (* Harvey P. Dale, Mar 20 2011 *)

Extensions

Edited by Max Alekseyev, Jul 31 2011

A245319 Numbers k that divide 2^k + 8.

Original entry on oeis.org

1, 2, 4, 5, 6, 8, 12, 18, 24, 36, 72, 88, 198, 228, 1032, 2412, 2838, 4553, 5958, 10008, 24588, 25938, 46777, 65538, 75468, 82505, 130056, 143916, 200364, 540738, 598818, 750852, 797478, 923628, 958212, 1151538, 1250568, 1505388, 1647396, 2365128, 2964036, 3490028, 3704418, 3844808
Offset: 1

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Author

Derek Orr, Jul 17 2014

Keywords

Examples

			2^4 + 8 = 24 is divisible by 4. Thus 4 is a term of this sequence.
2^5 + 8 = 40 is divisible by 5. Thus 5 is a term of this sequence.
		

Crossrefs

The odd terms form A357125.
Cf. A015922.

Programs

  • Maple
    select(n -> 2 &^ n + 8 mod n = 0, [$1..10^6]); # Robert Israel, Jul 18 2014
  • Mathematica
    Join[Select[Range[7],Divisible[2^#+8,#]&],Select[Range[4000000], Abs[ PowerMod[ 2,#,#]-#]==8&]] (* Harvey P. Dale, May 25 2016 *)
  • PARI
    for(n=1,10^9,if(Mod(2,n)^n==Mod(-8,n),print1(n,", ")));

A276967 Odd integers n such that 2^n == 2^3 (mod n).

Original entry on oeis.org

1, 3, 9, 15, 21, 33, 39, 51, 57, 63, 69, 87, 93, 111, 123, 129, 141, 159, 177, 183, 195, 201, 213, 219, 237, 249, 267, 291, 303, 309, 315, 321, 327, 339, 381, 393, 399, 411, 417, 447, 453, 471, 489, 501, 519, 537, 543, 573, 579, 591, 597, 633, 669, 681, 687, 693, 699, 717, 723, 731, 753, 771, 789, 807
Offset: 1

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Author

Max Alekseyev, Sep 22 2016

Keywords

Comments

Also, integers n such that 2^(n - 3) == 1 (mod n).
Contains A033553 as a subsequence. Smallest term greater than 3 missing in A033553 is 731.
For all m, 2^A015921(m) - 1 belongs to this sequence.

Crossrefs

The odd terms of A015922.
Odd integers n such that 2^n == 2^k (mod n): A176997 (k = 1), A173572 (k = 2), this sequence (k = 3), A033984 (k = 4), A276968 (k = 5), A215610 (k = 6), A276969 (k = 7), A215611 (k = 8), A276970 (k = 9), A215612 (k = 10), A276971 (k = 11), A215613 (k = 12).

Programs

  • Mathematica
    Join[{1}, Select[Range[1, 1023, 2], PowerMod[2, # - 3, #] == 1 &]] (* Alonso del Arte, Sep 22 2016 *)
  • PARI
    isok(n) = (n % 2) && (Mod(2,n)^n==8); \\ Michel Marcus, Sep 23 2016

A276969 Odd integers n such that 2^n == 2^7 (mod n).

Original entry on oeis.org

1, 3, 7, 15, 49, 91, 133, 217, 255, 259, 301, 427, 469, 511, 527, 553, 679, 721, 763, 889, 973, 1015, 1057, 1099, 1141, 1267, 1351, 1393, 1477, 1561, 1603, 1687, 1897, 1939, 1981, 2107, 2149, 2191, 2317, 2359, 2443, 2569, 2611, 2653, 2779, 2863, 2947, 3031, 3073, 3199, 3241, 3409, 3493, 3661, 3787
Offset: 1

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Author

Max Alekseyev, Sep 22 2016

Keywords

Comments

Also, integers n such that 2^(n-7) == 1 (mod n).
Contains A208155 as a subsequence.
For all m, 2^A015922(m)-1 belongs to this sequence.

Crossrefs

The odd terms of A015927.
Odd integers n such that 2^n == 2^k (mod n): A176997 (k=1), A173572 (k=2), A276967 (k=3), A033984 (k=4), A276968 (k=5), A215610 (k=6), this sequence (k=7), A215611 (k=8), A276970 (k=9), A215612 (k=10), A276971 (k=11), A215613 (k=12).

Programs

  • Mathematica
    m = 2^7; Join[Select[Range[1, m, 2], Divisible[2^# - m, #] &],
    Select[Range[m + 1, 10^3, 2], PowerMod[2, #, #] == m &]] (* Robert Price, Oct 12 2018 *)
  • PARI
    is(n)=n%2 && Mod(2,n)^n==128 \\ Charles R Greathouse IV, Sep 22 2016

A296370 Numbers m such that 2^m == 3/2 (mod m).

Original entry on oeis.org

1, 111481, 465793, 79036177, 1781269903307, 250369632905747, 708229497085909, 15673900819204067
Offset: 1

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Author

Max Alekseyev, Dec 11 2017

Keywords

Comments

Equivalently, 2^(m+1) == 3 (mod m).
Also, numbers m such that 2^(m+1) - 2 is a Fermat pseudoprime base 2, i.e., 2^(m+1) - 2 belongs to A015919 and A006935.
Some larger terms (may be not in order): 2338990834231272653581, 341569682872976768698011746141903924998969680637.

Crossrefs

Solutions to 2^m == k (mod m): this sequence (k=3/2), A187787 (k=1/2), A296369 (k=-1/2), A000079 (k=0), A006521 (k=-1), A015919 (k=2), A006517 (k=-2), A050259 (k=3), A015940 (k=-3), A015921 (k=4), A244673 (k=-4), A128121 (k=5), A245318 (k=-5), A128122 (k=6), A245728 (k=-6), A033981 (k=7), A240941 (k=-7), A015922 (k=8), A245319 (k=-8), A051447 (k=9), A240942 (k=-9), A128123 (k=10), A245594 (k=-10), A033982 (k=11), A128124 (k=12), A051446 (k=13), A128125 (k=14), A033983 (k=15), A015924 (k=16), A124974 (k=17), A128126 (k=18), A125000 (k=19), A015925 (k=2^5), A015926 (k=2^6), A015927 (k=2^7), A015929 (k=2^8), A015931 (k=2^9), A015932 (k=2^10), A015935 (k=2^11), A015937 (k=2^12)

Programs

  • Mathematica
    Select[Range[10^6], Divisible[2^(# + 1) - 3, #] &] (* Robert Price, Oct 11 2018 *)

Formula

a(n) = A296104(n) - 1.

A277344 3-Knödel numbers (A033553) that are not divisible by 3.

Original entry on oeis.org

50963, 5834755, 9835843, 155627923, 245056003, 332852435, 556268443, 724014203, 795650963, 831912763, 2440444163, 4080848203, 5067702643, 5140068643, 5555216803, 7461332483, 8438160643, 11766788323, 11951765003, 13058213003, 13483943203, 14528402983, 16644521435, 17847852803
Offset: 1

Views

Author

Max Alekseyev, Oct 09 2016

Keywords

Crossrefs

Intersection of A033553 and A242865.
Intersection of A033553 and A130133.
Subsequence of A015922.

A122711 Even numbers n such that n+2 divides n+2^n.

Original entry on oeis.org

106976, 1642796, 21879936, 96593696, 6926872352, 21235295216, 24936246176, 25867010016, 80832867116, 82230049056, 208329074876, 360598467776, 533800559216, 587627376176, 661575990912, 662312961696, 664490433776, 737374205276, 831623487276, 1052816473676, 1137732817376, 1213045642656, 1270015920636
Offset: 1

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Author

Zak Seidov, Sep 23 2006

Keywords

Comments

Same as even numbers n such that 2^n == 2 (mod n+2). - Robert G. Wilson v, Sep 27 2006
n must be a multiple of 4. A002326(n/4) must not be divisible by 2 or 3. If p is an odd prime factor of n+2, (n+2)/p mod A002326((p-1)/2)=3. - Martin Fuller, Oct 09 2006
Also, the positive numbers A015922(k)-2 that are multiples of 4. E.g., a(1) = 106976 = A015922(3926)-2. Hence, a(n)+2 forms a subsequence of A015922 (and of A130134) consisting of the terms congruent to 2 modulo 4. - Max Alekseyev, Apr 03 2014

Crossrefs

Programs

  • Mathematica
    Do[ If[ PowerMod[2, 2n, 2n + 2] == 2, Print@2n], {n, 10^9}] (* Robert G. Wilson v, Sep 27 2006 *)

Extensions

More terms from Max Alekseyev, Sep 23 2006, Oct 01 2006
More terms from Martin Fuller, Oct 09 2006
Terms a(18) onward from Max Alekseyev, Apr 09 2014
b-file corrected by Max Alekseyev, Oct 11 2016

A334634 Numbers m that divide 2^m + 11.

Original entry on oeis.org

1, 13, 16043199041, 91118493923, 28047837698634913
Offset: 1

Views

Author

Max Alekseyev, Sep 10 2020

Keywords

Comments

Equivalently, numbers m such that 2^m == -11 (mod m).
No other terms below 10^17.

Crossrefs

Solutions to 2^n == k (mod n): A296370 (k=3/2), A187787 (k=1/2), A296369 (k=-1/2), A000079 (k=0), A006521 (k=-1), A015919 (k=2), A006517 (k=-2), A050259 (k=3), A015940 (k=-3), A015921 (k=4), A244673 (k=-4), A128121 (k=5), A245318 (k=-5), A128122 (k=6), A245728 (k=-6), A033981 (k=7), A240941 (k=-7), A015922 (k=8), A245319 (k=-8), A051447 (k=9), A240942 (k=-9), A128123 (k=10), A245594 (k=-10), A033982 (k=11), this sequence (k=-11), A128124 (k=12), A051446 (k=13), A128125 (k=14), A033983 (k=15), A015924 (k=16), A124974 (k=17), A128126 (k=18), A125000 (k=19), A015925 (k=2^5), A015926 (k=2^6), A015927 (k=2^7), A015929 (k=2^8), A015931 (k=2^9), A015932 (k=2^10), A015935 (k=2^11), A015937 (k=2^12).

Extensions

a(5) from Sergey Paramonov, Oct 10 2021
Previous Showing 11-19 of 19 results.