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 1-4 of 4 results.

A116202 Numbers k such that k concatenated with k+6 gives the product of two numbers which differ by 8.

Original entry on oeis.org

7, 54, 234, 267, 894, 58227, 7962242238271227055830015496107, 60153956829051761181170060654114714579377214308482459, 2019668016997743800626449453386765007975459365956534868322001037107, 3031524678136833532602149525055953135725227119574025423809994922862
Offset: 1

Views

Author

Giovanni Resta, Feb 06 2006

Keywords

Examples

			58227//58233 = 76303 * 76311, where // denotes concatenation.
		

Crossrefs

Programs

  • Python
    from itertools import count, islice
    from sympy import sqrt_mod
    def A116202_gen(): # generator of terms
        for j in count(0):
            b = 10**j
            a = b*10+1
            for k in sorted(sqrt_mod(22,a,all_roots=True)):
                if a*(b-6) <= k**2-22 < a*(a-7) and k>4:
                    yield (k**2-22)//a
    A116202_list = list(islice(A116202_gen(),7)) # Chai Wah Wu, Feb 21 2024

Extensions

a(8)-a(10) from Chai Wah Wu, Feb 21 2024

A116197 Numbers k such that k concatenated with k+5 gives the product of two numbers which differ by 9.

Original entry on oeis.org

25, 2448207281, 2552334847, 9492271895, 10713024775597019390267617, 45251510049471045364918031, 99414584492459886818648287, 1000584180267191789271991959007645
Offset: 1

Views

Author

Giovanni Resta, Feb 06 2006

Keywords

Crossrefs

A116211 Numbers k such that k concatenated with k+7 gives the product of two numbers which differ by 9.

Original entry on oeis.org

1953, 3115, 6153, 1016574047215119910181525023, 2440558249789368730986767575, 2560156942576450203707692923, 4639822375038697733267413875, 4868700733912235016077891029
Offset: 1

Views

Author

Giovanni Resta, Feb 06 2006

Keywords

Examples

			6153//6160 = 7840 * 7849, where // denotes concatenation.
		

Crossrefs

A116334 n times n+9 gives the concatenation of two numbers m and m+6.

Original entry on oeis.org

45, 47, 3180, 3454, 6538, 6812, 32423077888994073533, 47028976905526474404, 49049512306209075907, 50950487693790924085, 52971023094473525588, 67576922111005926459, 71498432899270376140, 75216895567882908524
Offset: 1

Views

Author

Giovanni Resta, Feb 06 2006

Keywords

Examples

			6812 * 6821 = 4646//4652, where // denotes concatenation.
		

Crossrefs

Showing 1-4 of 4 results.