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 1-3 of 3 results.

A259432 Numbers n such that A259124(n) = A259124(n+1) > 0.

Original entry on oeis.org

14, 289, 308, 3624, 1153740, 1981716, 11704620, 12992625, 13093356, 52893876, 64160196, 93927036, 149603196, 194160876, 350423580, 510076212, 618962556, 647057796, 1015443660, 1896067572, 2038869276, 2137008660, 2603889372, 2661789732, 2878700052, 2941560492
Offset: 1

Views

Author

Alex Ratushnyak, Jun 26 2015

Keywords

Comments

Is the sequence infinite?
a(366) > 5 * 10^13. - Hiroaki Yamanouchi, Aug 24 2015

Examples

			A259124(14) = A259124(15) = 6, so 14 is a term.

Links

Crossrefs

Cf. A259124.

Extensions

a(17)-a(26) from Hiroaki Yamanouchi, Aug 24 2015

A259428 Numbers never appearing in A259124.

Original entry on oeis.org

1, 2, 3, 11, 27, 35, 51, 53, 79, 83, 89, 93, 117, 123, 125, 135, 143, 145, 161, 171, 173, 177, 179, 189, 197, 203, 205, 215, 219, 223, 233, 237, 249, 251, 255, 263, 267, 277, 287, 291, 293, 297, 303, 305, 321, 341, 343, 345, 353, 359, 363, 371, 373, 377, 383, 395, 407
Offset: 1

Views

Author

Alex Ratushnyak, Jun 26 2015

Keywords

Crossrefs

Cf. A259124.

A260093 Numbers n for which A259124(n) = A259124(n-1) + 1.

Original entry on oeis.org

20, 49, 2096, 5684, 14847, 440876, 18770091, 40882585915, 5598199195808, 35959924244180
Offset: 1

Views

Author

Alex Ratushnyak, Jul 15 2015

Keywords

Comments

Is the sequence infinite?
a(11) > 5 * 10^13. - Hiroaki Yamanouchi, Aug 24 2015

Crossrefs

Cf. A259124, A259432.

Programs

  • PARI
    a259124(n)=sum(y=2, sqrtint(n+1)-1, my(x=(n-y)/(y+1)); if(denominator(x)==1, x+y));
isok(n)= a259124(n) == a259124(n-1) + 1; \\ Michel Marcus, Aug 05 2015
  • Python
    TOP = 5000*5000
a = [0]*TOP
for y in range(2, 5000):
  z = TOP//y + 1
  for x in range(y, z):
    n = x*y + x + y
    if n>=TOP: break
    a[n] += x+y
for n in range(1,TOP):
    if a[n]==a[n-1]+1 and a[n]>0: print(n, end=', ')

Extensions

a(8)-a(9) from Hiroaki Yamanouchi, Aug 24 2015
a(10) from Hiroaki Yamanouchi, Aug 25 2015
Showing 1-3 of 3 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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