A075672 Duplicate of A069876.
1, 13, 405, 23058, 2078375, 271739011, 48574262275, 11373936899396
Offset: 1
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.
a(1) = 1^3 = 1; a(2) = 2^3 + 3^3 = 35; a(3) = 4^3 + 5^3 + 6^3 = 64 + 125 + 216 = 405. From _Philippe Deléham_, Mar 09 2014: (Start) a(1) = 1*2*3/8 = 1; a(2) = 8*5*7/8 = 35; a(3) = 27*10*12/8 = 405; a(4) = 64*17*19/8 = 2584; a(5) = 125*26*28/8 = 11375; etc. (End)
[(n^7+4*n^5+3*n^3)/8: n in [1..30]]; // Vincenzo Librandi, Mar 11 2014
A075664:=n->(n^7 + 4n^5 + 3n^3)/8; seq(A075664(n), n=1..30); # Wesley Ivan Hurt, Mar 10 2014
i1 := n(n-1)/2+1; i2 := n(n-1)/2+n; s=3; Table[Sum[i^s, {i, i1, i2}], {n, 20}] CoefficientList[Series[(1 + 27 x + 153 x^2 + 268 x^3 + 153 x^4 + 27 x^5 + x^6)/(1 - x)^8, {x, 0, 40}], x](* Vincenzo Librandi, Mar 11 2014 *) With[{nn=30},Total/@TakeList[Range[(nn(nn+1))/2]^3,Range[nn]]] (* Requires Mathematica version 11 or later *) (* or *) LinearRecurrence[{8,-28,56,-70,56,-28,8,-1},{1,35,405,2584,11375,38961,111475,278720},30] (* Harvey P. Dale, Jun 05 2021 *)
a(n)=(n^7+4*n^5+3*n^3)/8 \\ Charles R Greathouse IV, Oct 07 2015
def A075664(n): return n*(m:=n**2)*(m*(m+4)+3)>>3 # Chai Wah Wu, Feb 09 2025
a(1) = 1^10 = 1; a(2) = 2^10 + 3^10 = 60073; a(3) = 4^10 + 5^10 + 6^10 = 71280377; a(4) = 7^10 + 8^10 + 9^10 + 10^10 = 14843001474.
i1 := n(n-1)/2+1; i2 := n(n-1)/2+n; s=10; Table[Sum[i^s, {i, i1, i2}], {n, 20}] With[{nn=20},Total/@TakeList[Range[(nn(nn+1))/2]^10,Range[nn]]] (* Requires Mathematica version 11 or later *) (* Harvey P. Dale, Mar 18 2018 *)
a(1) = 1^4 = 1; a(2) = 2^4 + 3^4 = 97; a(3) = 4^4 + 5^4 + 6^4 = 2177; a(4) = 7^4 + 8^4 + 9^4 + 10^4 = 23058.
i1 := n(n-1)/2+1; i2 := n(n-1)/2+n; s=4; Table[Sum[i^s, {i, i1, i2}], {n, 20}] Table[Total[Range[(n(n+1))/2+1,((n+1)(n+2))/2]^4],{n,0,20}] (* or *) LinearRecurrence[{10,-45,120,-210,252,-210,120,-45,10,-1},{1,97,2177,23058,152979,738835,2839571,9191876,26037717,66301333},30] (* Harvey P. Dale, Dec 18 2015 *)
a(1) = 1^9 = 1; a(2) = 2^9 + 3^9 = 20195; a(3) = 4^9 + 5^9 + 6^9 = 12292965; a(4) = 7^9 + 8^9 + 9^9 + 10^9 = 1561991824.
[(5*n^19 + 105*n^17 + 666*n^15 + 1530*n^13 + 689*n^11 - 995*n^9 + 304*n^7 + 640*n^5 - 384*n^3)/2560 : n in [1..20]]; // Vincenzo Librandi, Oct 06 2011
i1 := n(n-1)/2+1; i2 := n(n-1)/2+n; s=9; Table[Sum[i^s, {i, i1, i2}], {n, 20}] Total[#^9]&/@(Range[First[#]+1,Last[#]]&/@Partition[Accumulate[Range[ 0,15]],2,1]) (* Harvey P. Dale, Oct 05 2011 *) With[{nn=20},Total/@TakeList[Range[(nn(nn+1))/2]^9,Range[nn]]] (* Harvey P. Dale, Aug 05 2025 *)
a(1) = 1^5 = 1; a(2) = 2^5 + 3^5 = 275; a(3) = 4^5 + 5^5 + 6^5 = 11925; a(4) = 7^5 + 8^5 + 9^5 + 10^5 = 208624.
i1 := n(n-1)/2+1; i2 := n(n-1)/2+n; s=5; Table[Sum[i^s, {i, i1, i2}], {n, 20}] nn=30;With[{p5=Range[((nn+1)(nn+2))/2]^5},Join[{1},Table[Total[Take[p5,{(n(n+1))/2+1,((n+1)(n+2))/2}]],{n,nn}]]] (* Harvey P. Dale, Mar 09 2014 *) Module[{nn=25,p5},p5=Range[(nn(nn+1))/2]^5;Total/@TakeList[p5,Range[nn]]] (* Harvey P. Dale, Oct 13 2023 *)
a(1) = 1^6 = 1; a(2) = 2^6 + 3^6 = 793; a(3) = 4^6 + 5^6 + 6^6 = 66377; a(4) = 7^6 + 8^6 + 9^6 + 10^6 = 1911234.
i1 := n(n-1)/2+1; i2 := n(n-1)/2+n; s=6; Table[Sum[i^s, {i, i1, i2}], {n, 20}] With[{nn=20},Total/@TakeList[Range[(nn(nn+1))/2]^6,Range[nn]]] (* or *) LinearRecurrence[{14,-91,364,-1001,2002,-3003,3432,-3003,2002,-1001,364,-91,14,-1},{1,793,66377,1911234,28504515,271739011,1874885963,10136389172,45311985069,173957200405,589679082421,1802148522758,5045944649967,13108508706879},20] (* Harvey P. Dale, Mar 29 2022 *)
a(1) = 1^7 = 1; a(2) = 2^7 + 3^7 = 2315; a(3) = 4^7 + 5^7 + 6^7 = 374445; a(4) = 7^7 + 8^7 + 9^7 + 10^7 = 17703664.
i1 := n(n-1)/2+1; i2 := n(n-1)/2+n; s=7; Table[Sum[i^s, {i, i1, i2}], {n, 20}]
a(1) = 1^8 = 1; a(2) = 2^8 + 3^8 = 6817; a(3) = 4^8 + 5^8 + 6^8 = 2135777; a(4) = 7^8 + 8^8 + 9^8 + 10^8 = 165588738.
i1 := n(n-1)/2+1; i2 := n(n-1)/2+n; s=8; Table[Sum[i^s, {i, i1, i2}], {n, 20}]