from django import template
from django.conf import settings

register = template.Library()

@register.filter
def adjust_for_pagination(value, page):
    value, page = int(value), int(page)
    adjusted_value = value + ((page - 1) * settings.RESULTS_PER_PAGE)
    return adjusted_value

# And the template snippet:
{% for object in object_list %}
<div class="serial-no">
    {% if is_paginated %}
        {{ forloop.counter|adjust_for_pagination:page }}
    {% else %}
       {{ forloop.counter }}
    {% endif %}
</div>
...
{% endfor %}