A031312 -id:A031312 - cp's OEIS frontend

A031321 Position of n-th 8 in A031312.

76, 78, 80, 82, 84, 217, 220, 223, 226, 229, 367, 370, 373, 376, 379, 517, 520, 523, 526, 529, 667, 670, 673, 676, 679, 817, 820, 823, 826, 829, 967, 970

Offset: 1

Clark Kimberling

nonn

A031322 Position of n-th 9 in A031312.

Original entry on oeis.org

5, 15, 25, 35, 45, 55, 65, 75, 85, 86, 88, 90, 92, 94, 95, 110, 125, 140, 155, 170, 185, 200, 215, 230, 232, 235, 238, 241, 244, 245, 260, 275, 290, 305, 320, 335, 350, 365, 380, 382, 385, 388, 391, 394, 395, 410, 425, 440, 455

Offset: 1

Clark Kimberling

nonn

A031323 Least k such that base 10 representation of n begins at s(k), where s=A031312.

Original entry on oeis.org

1, 16, 2, 36, 3, 56, 4, 76, 5, 96, 6, 17, 1, 37, 10, 57, 12, 77, 14, 246, 16, 276, 18, 306, 20, 336, 22, 366, 24, 396, 9, 19, 28, 39, 2, 59, 32, 79, 34, 546, 36, 576, 38, 606, 40, 636, 42, 666, 44, 696, 11, 21, 31, 41, 50, 61, 3, 81, 54, 846

Offset: 1

Clark Kimberling

nonn

A078259 a(n) = denominator(N), where N = 0.135..(2n-1) is the concatenation of the first n odd numbers after decimal point.

Original entry on oeis.org

10, 100, 200, 10000, 100000, 10000000, 1000000000, 20000000000, 10000000000000, 1000000000000000, 100000000000000000, 10000000000000000000, 40000000000000000000, 100000000000000000000000, 10000000000000000000000000, 1000000000000000000000000000

Offset: 1

Amarnath Murthy, Nov 24 2002

Cf. A019519, A031312.

a:= n-> (t-> denom(t/10^length(t)))(parse(cat(2*i-1$i=1..n))):
seq(a(n), n=1..16);  # Alois P. Heinz, Jun 25 2025

Corrected and extended by Sascha Kurz, Jan 04 2003

a(4)-a(5) corrected and more terms from Sean A. Irvine, Jun 25 2025

cp's OEIS Frontend

A031321 Position of n-th 8 in A031312.

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A031322 Position of n-th 9 in A031312.

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A031323 Least k such that base 10 representation of n begins at s(k), where s=A031312.

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A078259 a(n) = denominator(N), where N = 0.135..(2n-1) is the concatenation of the first n odd numbers after decimal point.

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