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.

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A131192 Numbers n >= 0 such that d(n) = (n^1 + 1)*(n^2 + 2)*...*(n^26 + 26) / 26! is nonintegral.

Original entry on oeis.org

7, 11, 18, 24, 29, 37, 40, 50, 51, 62, 73, 76, 84, 89, 95, 102, 106, 115, 128, 139, 141, 150, 154, 161, 167, 172, 180, 183, 193, 194, 205, 206, 216, 219, 227, 245, 249, 258, 260, 271, 282, 284, 293, 297, 304, 310, 315, 323, 326, 336, 337, 348, 349, 362, 370, 375, 381, 388, 392, 403, 414, 425, 427, 436
Offset: 1

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Comments

Notice that 26! = 2^23 * 3^10 * 5^6 * 7^3 * 11^2 * 13^2 * 17 * 19 * 23. There is no divisibility for 11^2 and n in {11m+7} \ {121m+117} and for 13^2 and n in {13m+11} \ {169m+63}. Therefore, this sequence is formed by the union ( {11m+7} \ {121m+117} ) U ( {13m+11} \ {169m+63}). - Max Alekseyev, Nov 10 2007

Crossrefs

Programs

  • Maple
    d:=proc(n) options operator, arrow: (product(n^j+j,j=1..26))/factorial(26) end proc: a:=proc(n) if type(d(n), integer) = false then n else end if end proc; seq(a(n),n=1..300); # Emeric Deutsch, Oct 24 2007

Extensions

Initial terms were calculated by Peter J. C. Moses; see comment in A129995
More terms from Emeric Deutsch, Oct 24 2007
More terms from Max Alekseyev, Feb 02 2015

A131677 a(n) = (Product_{i=1..7} n^i+i) / 7!.

Original entry on oeis.org

1, 8, 274725, 8903032600, 21521701559085, 9892478959203456, 1527238784041075105, 109733832449349303000, 4483781212288588835625, 118795734924428077310080, 2233888850312257843810061, 31811523551546985038211552, 359951182400070234774044725
Offset: 0

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Comments

See A131685 about well-definedness. - M. F. Hasler, May 02 2015

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Extensions

Definition made explicit by M. F. Hasler, May 02 2015

A131678 a(n) = (Product_{i=1..8} n^i+i) / 8!.

Original entry on oeis.org

1, 9, 9065925, 7310502643675, 176327300873583405, 483041091658815453456, 320648364425775841520065, 79074323113562613259765875, 9403175220694650942397475625, 639220975955961365494757841040, 27923612862792073359883606310061, 852385355738368243011331354210716, 19346552845649626158477975728463925
Offset: 0

Views

Author

Keywords

Comments

See A131685 about well-definedness. - M. F. Hasler, May 02 2015

Programs

Extensions

Definition made explicit by M. F. Hasler, May 02 2015
Previous Showing 11-13 of 13 results.