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 18 results. Next

A282107 Numbers n with k digits in base x (MSD(n)x=d_k, LSD(n)_x=d_1) such that, chosen one of their digits in position d_k < j < d_1, is Sum{i=j+1..k}{(i-j)*d_i} = Sum_{i=1..j-1}{(j-i)*d_i}. Case x = 2.

Original entry on oeis.org

5, 7, 10, 14, 17, 20, 21, 27, 28, 31, 34, 35, 39, 40, 42, 49, 54, 56, 57, 62, 65, 68, 70, 73, 78, 80, 84, 85, 93, 98, 99, 107, 108, 112, 114, 119, 124, 127, 130, 133, 136, 140, 141, 146, 147, 155, 156, 160, 161, 167, 168, 170, 175, 177, 186, 196, 198, 201, 214
Offset: 1

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Author

Paolo P. Lava, Feb 06 2017

Keywords

Comments

All the palindromic numbers in base 2 with an odd number of digits belong to the sequence.
Here the fulcrum is one of the digits while in the sequence from A282143 to A282151 is between two digits.

Examples

			897 in base 2 is 1110000001. If j = 7 (the first 0 from left) we have 1*1 + 1*2 + 1*3 = 6 for the left side and 0*1 + 0*2 + 0*3 + 0*4 + 0*5 + 1*6 = 6 for the right one.
		

Crossrefs

Programs

  • Maple
    P:=proc(n,h) local a,j,k: a:=convert(n, base, h):
    for k from 1 to nops(a)-1 do
    if add(a[j]*(k-j),j=1..k)=add(a[j]*(j-k),j=k+1..nops(a))
    then RETURN(n); break: fi: od: end: seq(P(i,2),i=1..10^3);

A282143 Numbers n with k digits in base x (MSD(n)=d_k, LSD(n)=d_1) such that, chosen one of their digits in position d_k < j < d_1, is Sum_{i=j..k}{(i-j+1)*d_i} = Sum_{i=1..j-1}{(j-i)*d_i}. Case x = 2.

Original entry on oeis.org

3, 6, 9, 12, 15, 18, 19, 24, 25, 30, 33, 36, 38, 45, 48, 50, 51, 60, 63, 66, 69, 72, 75, 76, 81, 87, 90, 96, 100, 102, 105, 117, 120, 126, 129, 131, 132, 138, 143, 144, 150, 152, 153, 162, 165, 174, 179, 180, 189, 192, 193, 195, 200, 204, 205, 210, 219, 231, 234
Offset: 1

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Author

Keywords

Comments

All the palindromic numbers in base 2 with an even number of digits belong to the sequence.
Here the fulcrum is between two digits while in the sequence from A282107 to A282115 is one of the digits.

Examples

			143 in base 2 is 10001111. If we split the number in 10001 and 111 we have 1*1 + 0*2 + 0*3 + 0*4 + 1*5 = 6 for the left side and 1*1 + 1*2 + 1*3 = 6 for the right one.
		

Crossrefs

Programs

  • Maple
    P:=proc(n,h) local a,j,k: a:=convert(n, base, h):
    for k from 1 to nops(a)-1 do
    if add(a[j]*(k-j+1),j=1..k)=add(a[j]*(j-k),j=k+1..nops(a))
    then RETURN(n); break: fi: od: end: seq(P(i,2),i=1..10^3);

A282151 Numbers n with k digits in base x (MSD(n)=d_k, LSD(n)=d_1) such that, chosen one of their digits in position d_k < j < d_1, is Sum_{i=j..k}{(i-j+1)*d_i} = Sum_{i=1..j-1}{(j-i)*d_i}. Case x = 10.

Original entry on oeis.org

11, 22, 33, 44, 55, 66, 77, 88, 99, 102, 110, 113, 124, 135, 146, 157, 168, 179, 201, 204, 215, 220, 226, 237, 248, 259, 306, 311, 317, 328, 330, 339, 402, 408, 419, 421, 440, 512, 531, 550, 603, 622, 641, 660, 713, 732, 751, 770, 804, 823, 842, 861, 880, 914, 933
Offset: 1

Views

Author

Paolo P. Lava, Feb 15 2017

Keywords

Comments

All the palindromic numbers in base 10 with an even number of digits belong to the sequence.
Here the fulcrum is between two digits while in the sequence from A282107 to A282115 is one of the digits.

Examples

			If we split 2039 in 203 and 9 we have 3*1 + 0*2 + 2*3 = 9 for the left side and 9*1 = 9 for the right one.
		

Crossrefs

Programs

  • Maple
    P:=proc(n,h) local a,j,k: a:=convert(n, base, h):
    for k from 1 to nops(a)-1 do
    if add(a[j]*(k-j+1),j=1..k)=add(a[j]*(j-k),j=k+1..nops(a))
    then RETURN(n); break: fi: od: end: seq(P(i,10),i=1..10^3);

A282108 Numbers n with k digits in base x (MSD(n)=d_k, LSD(n)=d_1) such that, chosen one of their digits in position d_k < j < d_1, is Sum_{i=j+1..k}{(i-j)*d_i} = Sum_{i=1..j-1}{(j-i)*d_i}. Case x = 3.

Original entry on oeis.org

10, 13, 16, 20, 23, 26, 29, 30, 32, 35, 39, 48, 55, 60, 64, 69, 73, 78, 82, 87, 90, 91, 96, 100, 105, 112, 117, 121, 130, 137, 142, 144, 146, 151, 155, 160, 164, 165, 169, 173, 178, 180, 182, 187, 192, 194, 203, 207, 212, 219, 224, 233, 234, 242, 246, 247, 256
Offset: 1

Views

Author

Paolo P. Lava, Feb 06 2017

Keywords

Comments

All the palindromic numbers in base 3 with an odd number of digits belong to the sequence.
Here the fulcrum is one of the digits while in the sequence from A282143 to A282151 is between two digits.

Examples

			35 in base 3 is 1022. If j = 2 (second 2 from the right) we have 0*1 + 1*2 = 2 for the left side and 2*1 for the right one.
		

Crossrefs

Programs

  • Maple
    P:=proc(n,h) local a,j,k: a:=convert(n, base, h):
    for k from 1 to nops(a)-1 do
    if add(a[j]*(k-j),j=1..k)=add(a[j]*(j-k),j=k+1..nops(a))
    then RETURN(n); break: fi: od: end: seq(P(i,3),i=1..10^3);

A282109 Numbers n with k digits in base x (MSD(n)=d_k, LSD(n)=d_1) such that, chosen one of their digits in position d_k < j < d_1, is Sum_{i=j+1..k}{(i-j)*d_i} = Sum_{i=1..j-1}{(j-i)*d_i}. Case x = 4.

Original entry on oeis.org

17, 21, 25, 29, 34, 38, 42, 46, 51, 55, 59, 63, 66, 68, 70, 74, 78, 83, 84, 87, 91, 95, 100, 116, 129, 136, 145, 152, 161, 168, 177, 184, 197, 204, 213, 220, 229, 236, 245, 252, 257, 259, 263, 264, 267, 271, 272, 273, 280, 289, 296, 305, 312, 325, 332, 336, 341
Offset: 1

Views

Author

Paolo P. Lava, Feb 06 2017

Keywords

Comments

All the palindromic numbers in base 4 with an odd number of digits belong to the sequence.
Here the fulcrum is one of the digits while in the sequence from A282143 to A282151 is between two digits.

Examples

			83 in base 4 is 1103. If j = 2 (digit 0) we have 1*1 + 1*2 = 3 for the left side and 3*1 = 3 for the right one.
		

Crossrefs

Programs

  • Maple
    P:=proc(n,h) local a,j,k: a:=convert(n, base, h):
    for k from 1 to nops(a)-1 do
    if add(a[j]*(k-j),j=1..k)=add(a[j]*(j-k),j=k+1..nops(a)) then
    RETURN(n); break: fi: od: end: seq(P(i,4),i=1..10^3);

A282110 Numbers n with k digits in base x (MSD(n)=d_k, LSD(n)=d_1) such that, chosen one of their digits in position d_k < j < d_1, is Sum_{i=j+1..k}{(i-j)*d_i} = Sum_{i=1..j-1}{(j-i)*d_i}. Case x = 5.

Original entry on oeis.org

26, 31, 36, 41, 46, 52, 57, 62, 67, 72, 78, 83, 88, 93, 98, 104, 109, 114, 119, 124, 127, 130, 132, 137, 142, 147, 153, 155, 158, 163, 168, 173, 179, 180, 184, 189, 194, 199, 205, 230, 251, 254, 259, 260, 264, 269, 274, 276, 285, 301, 310, 326, 335, 351, 360, 381
Offset: 1

Views

Author

Paolo P. Lava, Feb 06 2017

Keywords

Comments

All the palindromic numbers in base 5 with an odd number of digits belong to the sequence.
Here the fulcrum is one of the digits while in the sequence from A282143 to A282151 is between two digits.
Numbers with this property in all the bases from 2 to 5 are: 78, 650, 1550, 4368, 4433, 4805, 6913, 7410, 16709, 31824, 35175, 41216, 104272, 107584, 132285, 144781, 165059, 173305, 174096, 190468, 195473, 201900, 205005, 205261, 214432, 231521, 243984, 275026, 278528, 295275, 304562, 313769, ...

Examples

			137 in base 5 is 1022. If j=2 (the second 2 from right) we have 0*1 + 1*2 = 2 for the left side and 2*1 = 2 for the right one.
		

Crossrefs

Programs

  • Maple
    P:=proc(n,h) local a,j,k: a:=convert(n, base, h):
    for k from 1 to nops(a)-1 do
    if add(a[j]*(k-j),j=1..k)=add(a[j]*(j-k),j=k+1..nops(a)) then
    RETURN(n); break: fi: od: end: seq(P(i,5),i=1..10^3);

A282111 Numbers n with k digits in base x (MSD(n)=d_k, LSD(n)=d_1) such that, chosen one of their digits in position d_k < j < d_1, is Sum_{i=j+1..k}{(i-j)*d_i} = Sum_{i=1..j-1}{(j-i)*d_i}. Case x = 6.

Original entry on oeis.org

37, 43, 49, 55, 61, 67, 74, 80, 86, 92, 98, 104, 111, 117, 123, 129, 135, 141, 148, 154, 160, 166, 172, 178, 185, 191, 197, 203, 209, 215, 218, 222, 224, 230, 236, 242, 248, 255, 258, 261, 267, 273, 279, 285, 292, 294, 298, 304, 310, 316, 322, 329, 330, 335, 341
Offset: 1

Views

Author

Paolo P. Lava, Feb 06 2017

Keywords

Comments

All the palindromic numbers in base 6 with an odd number of digits belong to the sequence.
Here the fulcrum is one of the digits while in the sequence from A282143 to A282151 is between two digits.
Numbers with this property in all the bases from 2 to 6 are:
144781, 345440, 743687, 1650704, 4020912, 4270149, 4757093, 6922591, 7102553, 7406643, 7677171, 7823009, 8853188, 12444016, 14457746, 14853520, 14861718, 15794512, 15994195, 17375742, 20450682, 20802565, 22173561, 22186557, 25268754, 261656297, 26648201, 27740672, ...

Examples

			304 in base 6 is 1224. If j = 2 (the first 2 from right) we have 2*1 + 1*2 = 4 for the left side and 4*1 = 4 for the right one.
		

Crossrefs

Programs

  • Maple
    P:=proc(n,h) local a,j,k: a:=convert(n, base, h):
    for k from 1 to nops(a)-1 do
    if add(a[j]*(k-j),j=1..k)=add(a[j]*(j-k),j=k+1..nops(a)) then
    RETURN(n); break: fi: od: end: seq(P(i,6),i=1..10^3);

A282112 Numbers n with k digits in base x (MSD(n)=d_k, LSD(n)=d_1) such that, chosen one of their digits in position d_k < j < d_1, is Sum_{i=j+1..k}{(i-j)*d_i} = Sum_{i=1..j-1}{(j-i)*d_i}. Case x = 7.

Original entry on oeis.org

50, 57, 64, 71, 78, 85, 92, 100, 107, 114, 121, 128, 135, 142, 150, 157, 164, 171, 178, 185, 192, 200, 207, 214, 221, 228, 235, 242, 250, 257, 264, 271, 278, 285, 292, 300, 307, 314, 321, 328, 335, 342, 345, 350, 352, 359, 366, 373, 380, 387, 395, 399, 402, 409
Offset: 1

Views

Author

Paolo P. Lava, Feb 06 2017

Keywords

Comments

All the palindromic numbers in base 7 with an odd number of digits belong to the sequence.
Here the fulcrum is one of the digits while in the sequence from A282143 to A282151 is between two digits.
Numbers with this property in all the bases from 2 to 7 are: 53060873, 55161152, 151009636, 343518281, 505587488, 513015908, ...- Giovanni Resta, Feb 13 2017

Examples

			409 in base 7 is 1123. If j = 2 (digit 2) we have 1*1 + 1*2 = 3 for the left side and 3*1 = 3 for the right one.
		

Crossrefs

Programs

  • Maple
    P:=proc(n,h) local a,j,k: a:=convert(n, base, h):
    for k from 1 to nops(a)-1 do
    if add(a[j]*(k-j),j=1..k)=add(a[j]*(j-k),j=k+1..nops(a)) then
    RETURN(n); break: fi: od: end: seq(P(i,7),i=1..10^3);

A282113 Numbers n with k digits in base x (MSD(n)=d_k, LSD(n)=d_1) such that, chosen one of their digits in position d_k < j < d_1, is Sum_{i=j+1..k}{(i-j)*d_i} = Sum_{i=1..j-1}{(j-i)*d_i}. Case x = 8.

Original entry on oeis.org

65, 73, 81, 89, 97, 105, 113, 121, 130, 138, 146, 154, 162, 170, 178, 186, 195, 203, 211, 219, 227, 235, 243, 251, 260, 268, 276, 284, 292, 300, 308, 316, 325, 333, 341, 349, 357, 365, 373, 381, 390, 398, 406, 414, 422, 430, 438, 446, 455, 463, 471, 479, 487, 495
Offset: 1

Views

Author

Paolo P. Lava, Feb 06 2017

Keywords

Comments

All the palindromic numbers in base 8 with an odd number of digits belong to the sequence.
Here the fulcrum is one of the digits while in the sequence from A282143 to A282151 is between two digits.
Numbers with this property in all the bases from 2 to 8 are: 2438269535, 6936679443, 8657968788, 11107027008, 21733512704, ... - Giovanni Resta, Feb 13 2017

Examples

			1084 in base 8 is 2074. If j = 2 (digit 7) we have 0*1 + 2*2 = 4 for the left side and 4*1 = 4 for the right one.
		

Crossrefs

Programs

  • Maple
    P:=proc(n,h) local a,j,k: a:=convert(n, base, h):
    for k from 1 to nops(a)-1 do
    if add(a[j]*(k-j),j=1..k)=add(a[j]*(j-k),j=k+1..nops(a)) then
    RETURN(n); break:fi: od: end: seq(P(i,8),i=1..10^3);

A282114 Numbers n with k digits in base x (MSD(n)=d_k, LSD(n)=d_1) such that, chosen one of their digits in position d_k < j < d_1, is Sum_{i=j+1..k}{(i-j)*d_i} = Sum_{i=1..j-1}{(j-i)*d_i}. Case x = 9.

Original entry on oeis.org

82, 91, 100, 109, 118, 127, 136, 145, 154, 164, 173, 182, 191, 200, 209, 218, 227, 236, 246, 255, 264, 273, 282, 291, 300, 309, 318, 328, 337, 346, 355, 364, 373, 382, 391, 400, 410, 419, 428, 437, 446, 455, 464, 473, 482, 492, 501, 510, 519, 528, 537, 546, 555
Offset: 1

Views

Author

Paolo P. Lava, Feb 06 2017

Keywords

Comments

All the palindromic numbers in base 9 with an odd number of digits belong to the sequence.
Here the fulcrum is one of the digits while in the sequence from A282143 to A282151 is between two digits.
Numbers with this property in all the bases from 2 to 9 are:
898958160865, 1518029154732,... - Giovanni Resta, Feb 13 2017

Examples

			3485 in base 9 is 4702. If j = 3 (digit 7) we have 4*1 = 4 for tyhe left side and 0*1 + 2*2 = 4 for the right one.
		

Crossrefs

Programs

  • Maple
    P:=proc(n,h) local a,j,k: a:=convert(n, base, h):
    for k from 1 to nops(a)-1 do
    if add(a[j]*(k-j),j=1..k)=add(a[j]*(j-k),j=k+1..nops(a)) then
    RETURN(n); break: fi: od: end: seq(P(i,9),i=1..10^3);
Showing 1-10 of 18 results. Next