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.
%I A383535 #6 May 21 2025 16:41:48 %S A383535 1,2,3,2,5,4,7,2,3,6,11,4,13,10,6,2,17,4,19,6,9,14,23,4,5,22,3,10,29, %T A383535 8,31,2,15,26,10,4,37,34,21,6,41,12,43,14,6,38,47,4,7,6,33,22,53,4,15, %U A383535 10,39,46,59,8,61,58,9,2,25,20,67,26,51,12,71,4,73 %N A383535 Heinz number of the positive first differences of the 0-prepended prime indices of n. %C A383535 The Heinz number of a partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k). This gives a bijective correspondence between positive integers and integer partitions. %C A383535 Also Heinz number of the first differences of the distinct 0-prepended prime indices of n. %F A383535 A001222(a(n)) = A001221(n). %F A383535 A056239(a(n)) = A061395(n). %F A383535 A055396(a(n)) = A055396(n). %F A383535 A061395(a(n)) = A241919(n). %e A383535 The terms together with their prime indices begin: %e A383535 1: {} 2: {1} 31: {11} 38: {1,8} %e A383535 2: {1} 17: {7} 2: {1} 47: {15} %e A383535 3: {2} 4: {1,1} 15: {2,3} 4: {1,1} %e A383535 2: {1} 19: {8} 26: {1,6} 7: {4} %e A383535 5: {3} 6: {1,2} 10: {1,3} 6: {1,2} %e A383535 4: {1,1} 9: {2,2} 4: {1,1} 33: {2,5} %e A383535 7: {4} 14: {1,4} 37: {12} 22: {1,5} %e A383535 2: {1} 23: {9} 34: {1,7} 53: {16} %e A383535 3: {2} 4: {1,1} 21: {2,4} 4: {1,1} %e A383535 6: {1,2} 5: {3} 6: {1,2} 15: {2,3} %e A383535 11: {5} 22: {1,5} 41: {13} 10: {1,3} %e A383535 4: {1,1} 3: {2} 12: {1,1,2} 39: {2,6} %e A383535 13: {6} 10: {1,3} 43: {14} 46: {1,9} %e A383535 10: {1,3} 29: {10} 14: {1,4} 59: {17} %e A383535 6: {1,2} 8: {1,1,1} 6: {1,2} 8: {1,1,1} %t A383535 prix[n_]:=If[n==1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]]; %t A383535 Table[Times@@Prime/@DeleteCases[Differences[Prepend[prix[n],0]],0],{n,100}] %Y A383535 For multiplicities instead of differences we have A181819. %Y A383535 Positions of first appearances are A358137. %Y A383535 Positions of squarefree numbers are A383512, counted by A098859. %Y A383535 Positions of nonsquarefree numbers are A383513, counted by A336866. %Y A383535 These are Heinz numbers of rows of A383534. %Y A383535 A000040 lists the primes, differences A001223. %Y A383535 A048767 is the Look-and-Say transform, union A351294, complement A351295. %Y A383535 A056239 adds up prime indices, row sums of A112798, counted by A001222. %Y A383535 A320348 counts strict partitions with distinct 0-appended differences, ranks A325388. %Y A383535 A325324 counts partitions with distinct 0-appended differences, ranks A325367. %Y A383535 Cf. A122111, A124010 (prime signature), A130091, A287352, A325351, A325366, A325368, A355536, A381431, A384008, A384009. %K A383535 nonn %O A383535 1,2 %A A383535 _Gus Wiseman_, May 21 2025