login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A214961 a(0)=a(1)=1, a(n) = least k>a(n-1) such that k*a(n-2) is a triangular number. 5
1, 1, 3, 6, 7, 11, 13, 21, 25, 30, 49, 59, 97, 117, 193, 233, 385, 465, 492, 596, 983, 1191, 1965, 2381, 2516, 4761, 5031, 5761, 6290, 8466, 9795, 15470, 15867, 17403, 20559, 24170, 26945, 27192, 27755, 30130, 35235, 43537, 45100, 56805, 58717, 58739, 91000, 117477 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..47.

PROG

(Python)

prpr = prev = 1

for n in range(1, 55):

    print prpr,

    b = k = 0

    while k<=prev:

        d = b*(b+1)/2

        k = 0

        if d%prpr==0:

            k = d / prpr

        b += 1

    prpr = prev

    prev = k

CROSSREFS

Cf. A214914, A214915, A214916, A214963, A213005.

Sequence in context: A153033 A282167 A076644 * A189626 A297292 A087642

Adjacent sequences:  A214958 A214959 A214960 * A214962 A214963 A214964

KEYWORD

nonn

AUTHOR

Alex Ratushnyak, Aug 03 2012

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 22 10:07 EDT 2019. Contains 321421 sequences. (Running on oeis4.)