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 1-5 of 5 results.

A116099 Numbers k such that k concatenated with k-9 gives the product of two numbers which differ by 7.

Original entry on oeis.org

69, 59898667, 79493157, 13412927190959690154913903, 14163000698458955079906403, 38895475965785687555173929, 40165600438484442828161229, 74294440818366638194239027
Offset: 1

Views

Author

Giovanni Resta, Feb 06 2006

Keywords

Comments

Also numbers k such that k concatenated with k-3 gives the product of two numbers which differ by 5.
Also numbers k such that k concatenated with k+1 gives the product of two numbers which differ by 3.
Also numbers k such that k concatenated with k+3 gives the product of two numbers which differ by 1.

Examples

			79493157//79493154 = 89158933 * 89158938, where // denotes concatenation.
79493157//79493158 = 89158934 * 89158937.
79493157//79493160 = 89158935 * 89158936.
79493157//79493148 = 89158932 * 89158939.
		

Crossrefs

Extensions

Edited by N. J. A. Sloane, Apr 12 2007

A116267 Numbers k such that k*(k+4) gives the concatenation of two numbers m and m-3.

Original entry on oeis.org

8, 98, 426, 571, 725, 844, 998, 7808, 9998, 36363, 63634, 99998, 326732, 673265, 999998, 4545452, 5454545, 9999998, 47058821, 52941176, 99999998, 331983805, 332667332, 384615384, 422892896, 475524475, 524475522, 577107101, 615384613, 667332665, 668016192, 719964244
Offset: 1

Views

Author

Giovanni Resta, Feb 06 2006

Keywords

Crossrefs

Programs

  • Python
    from itertools import count, islice
    from sympy import sqrt_mod
    def A116267_gen(): # generator of terms
        for j in count(0):
            b = 10**j
            a = b*10+1
            for k in sorted(sqrt_mod(1,a,all_roots=True)):
                if a*(b+3) <= k**2-1 < a*(a+2):
                    yield k-2
    A116267_list = list(islice(A116267_gen(),20)) # Chai Wah Wu, Feb 19 2024

Extensions

a(29)-a(32) from Chai Wah Wu, Feb 19 2024

A116261 Numbers k such that k*(k+5) gives the concatenation of two numbers m and m-4.

Original entry on oeis.org

7, 97, 766, 857, 909, 997, 3284, 6712, 9997, 45451, 54545, 99997, 990099, 999997, 8181818, 9999997, 70588232, 99999997, 343130553, 362637362, 363636360, 420053630, 421052631, 497975708, 502024288, 578947365, 579946366
Offset: 1

Views

Author

Giovanni Resta, Feb 06 2006

Keywords

Crossrefs

A116269 Numbers k such that k*(k+7) gives the concatenation of two numbers m and m-3.

Original entry on oeis.org

87, 3675, 6319, 8785, 48742, 51252, 87616, 3762553, 6237441, 9217099, 3266298273, 3520463763, 6479536231, 6733701721, 8063694647, 8317860137, 4689524709430934473, 5310475290569065521, 7416797436703661746
Offset: 1

Views

Author

Giovanni Resta, Feb 06 2006

Keywords

Crossrefs

A116276 Numbers k such that k*(k+5) gives the concatenation of two numbers m and m-2.

Original entry on oeis.org

70, 79822843, 69852478553064869297984899963805, 77473062193002372448027740546437, 77747359197583788609974143907617, 84341826458653210947638195982113, 85367942837521291760016984490249
Offset: 1

Views

Author

Giovanni Resta, Feb 06 2006

Keywords

Examples

			79822843 * 79822848 = 63716866//63716864, where // denotes concatenation.
		

Crossrefs

Showing 1-5 of 5 results.